Psychology/ Powerpoint Slides/ 5 -7 slides/ Use more graphics less words

CHAPTER 2 Biological Beginnings CHAPTER OUTLINE • THE EVOLUTIONARY PERSPECTIVE • Natural Selection and Adaptive Behavior

• Evolutionary Psychology

• GENETIC FOUNDATIONS OF DEVELOPMENT • Genes and Chromosomes

• Genetic Principles

• Chromosome and Gene-Linked Abnormalities

• THE INTERACTION OF HEREDITY AND ENVIRONMENT: THE NATURE- NURTURE DEBATE • Behavior Genetics

• Heredity-Environment Correlations

• The Epigenetic View and Gene × Environment (G × E) Interaction

• Conclusions About Heredity-Environment Interaction

• PRENATAL DEVELOPMENT • The Course of Prenatal Development

• Prenatal Tests

• Infertility and Reproductive Technology

• Hazards to Prenatal Development

• Prenatal Care

• BIRTH AND THE POSTPARTUM PERIOD • The Birth Process

• The Transition from Fetus to Newborn

• Low Birth Weight and Preterm Infants

• Bonding

• The Postpartum Period

Stories of Life-Span Development: The Jim and Jim Twins Jim Springer and Jim Lewis are identical twins. They were separated at 4 weeks of age and did

not see each other again until they were 39 years old. Both worked as part-time deputy sheriffs,

vacationed in Florida, drove Chevrolets, had dogs named Toy, and married and divorced women

named Betty. One twin named his son James Allan, and the other named his son James Alan.

Both liked math but not spelling, enjoyed carpentry and mechanical drawing, chewed their

fingernails down to the nubs, had almost identical drinking and smoking habits, had

hemorrhoids, put on 10 pounds at about the same point in development, first suffered headaches

at the age of 18, and had similar sleep patterns.

Jim and Jim do have some differences. One wears his hair over his forehead, the other slicks it

back and has sideburns. One expresses himself best orally; the other is more proficient in

writing. But, for the most part, their profiles are remarkably similar.

Another pair of identical twins, Daphne and Barbara, were called the “giggle sisters”

by researchers because after being reunited they were always making each other laugh.

A thorough search of their adoptive families’ histories revealed no gigglers. The giggle Page

36 sisters ignored stress, avoided conflict and controversy whenever possible, and showed

no interest in politics.

Jim and Jim and the giggle sisters were part of the Minnesota Study of Twins Reared Apart,

directed by Thomas Bouchard and his colleagues. The study brings identical twins (who are

identical genetically because they come from the same fertilized egg) and fraternal twins (who

come from different fertilized eggs) from all over the world to Minneapolis to investigate their

lives. There the twins complete personality and intelligence tests, and provide detailed medical

histories, including information about diet and smoking, exercise habits, chest X-rays, heart

stress tests, and EEGs. The twins are asked more than 15,000 questions about their family and

childhood, personal interests, vocational orientation, values, and aesthetic judgments (Bouchard

& others, 1990).

When genetically identical twins who were separated as infants show such striking similarities in

their tastes and habits and choices, can we conclude that their genes must have caused these

similarities? Although genes play a role, we also need to consider other possible causes. The

twins shared not only the same genes but also some similar experiences. Some of the separated

twins lived together for several months prior to their adoption; some had been reunited prior to

testing (in some cases, many years earlier); adoption agencies often place twins in similar homes;

and even strangers who spend several hours together and start comparing their lives are likely to

come up with some coincidental similarities (Joseph, 2006).

The Minnesota study of identical twins points to both the importance of the genetic basis of

human development and the need for further research on genetic and environmental factors.

The examples of Jim and Jim and the giggle sisters stimulate us to think about our genetic

heritage and the biological foundations of our existence. Organisms are not like billiard balls,

moved by simple, external forces to predictable positions on life’s pool table. Environmental

experiences and biological foundations work together to make us who we are. Our coverage of

life’s biological beginnings and experiences will emphasize the evolutionary perspective; genetic

foundations; the interaction of heredity and environment; and charting growth from conception

through the prenatal period, the birth process itself, and the postpartum period that

follows birth. ■

Genetic Foundations of Development Genetic influences on behavior evolved over time and across many species. Our many traits and characteristics that are genetically influenced have a long evolutionary history that is retained in our DNA. In other Page 39 words, our DNA is not just inherited from

our parents; it’s also what we’ve inherited as a species from the species that came before our own. Let’s take a closer look at DNA and its role in human development. How are characteristics that suit a species for survival transmitted from one generation to the next? Darwin did not know the answer to this question because genes and the principles of genetics had not yet been discovered. Each of us carries a human “genetic code” that we inherited from our parents. Because a fertilized egg carries this human code, a fertilized human egg cannot grow into an egret, eagle, or elephant.

Each of us began life as a single cell weighing about one twenty-millionth of an ounce. This tiny piece of matter housed our entire genetic code—instructions that orchestrated growth from that single cell to a person made of trillions of cells, each containing a replica of the original code. That code is carried by our genes. What are genes and what do they do? For the answer, we need to look into our cells.

The nucleus of each human cell contains chromosomes, which are threadlike structures made up of deoxyribonucleic acid, or DNA. DNA is a complex molecule that has a double helix shape, like a spiral staircase, and contains genetic information. Genes, the units of hereditary information, are short segments of DNA, as you can see in Figure 2. They help cells to reproduce themselves and to assemble proteins. Proteins, in turn, are the building blocks of cells as well as the regulators that direct the body’s processes (Cowan, 2015; Goodenough & McGuire, 2017).

Figure 2 Cells, Chromosomes, DNA,

and Genes

(Top) The body contains trillions of cells. Each cell contains a central structure, the

nucleus. (Middle) Chromosomes are threadlike structures located in the nucleus of the cell.

Chromosomes are composed of DNA. (Bottom) DNA has the structure of a spiral staircase. A gene is a segment of DNA.

Each gene has its own designated place on a particular chromosome. Today, there is a great deal of enthusiasm about efforts to discover the specific locations of genes that are linked to certain functions and developmental outcomes (Johnson, 2017; Sutphin & Korstanje, 2016). An important step in this direction was taken when the Human Genome Project and the Celera Corporation completed a preliminary map of the human genome—the complete set of developmental instructions for creating proteins that initiate the making of a human organism (Brooker, 2015). Completion of the Human Genome Project has led to use of the genome-wide association method to identify genetic variations linked to a particular disease, such as cancer, cardiovascular disease, or Alzheimer disease (Cho & Suh, 2016; Hou & others, 2016). To conduct a genome-wide association study, researchers obtain DNA from individuals who have the disease and those who don’t have it. Then, each participant’s complete set of DNA, or genome, is purified from the blood or other cells and scanned on machines to determine markers of genetic variation. If the genetic variations occur more frequently in people who have the disease than in those who don’t have it, the variations point to the region in the human genome where the disease-causing problem exists. Genome- wide association studies have recently been conducted for childhood obesity (Zandona & others, 2016); cancer (Johnson & others, 2016); cardiovascular disease (Schick & others, 2016); depression (Knowles & others, 2016; Nho & others, 2015); suicide (Sokolowski, Wasserman, & Wasserman, 2016); glaucoma (Bailey & others, 2016); and Alzheimer disease (Chauhan & others, 2015; Ramos Dos Santos & others, 2016). One of the big surprises of the Human Genome Project was a report indicating that humans have only about 30,000 genes (U.S. Department of Energy, 2001). More recently, the number of human genes has been revised further downward, to approximately 20,700 (Flicek & others, 2013). Further recent analysis proposes that humans may actually have Page 40fewer than 20,000 protein-producing genes (Ezkurida & others, 2014). Scientists had thought that humans had as many as 100,000 or more genes. They had also believed that each gene programmed just one protein. In fact, humans appear to have far more proteins than they have genes, so there cannot be a one-to-one correspondence between genes and proteins (Commoner, 2002). Each gene is not translated, in automaton-like fashion, into one and only one protein. A gene does not act independently, as developmental psychologist David Moore (2001) emphasized by titling his book The Dependent Gene. Rather than being a group of independent genes, the human genome consists of many genes that collaborate both with each other and with nongenetic factors inside and outside the body. The collaboration operates at many points. For example, the cellular “machinery” mixes, matches, and links small pieces of DNA to reproduce the genes, and that machinery is influenced by what is going on around it (Moore, 2015). Whether a gene is turned “on”—that is, working to assemble proteins—is also a matter of collaboration. The activity of genes (genetic expression) is affected by their environment (Gottlieb, 2007; Moore, 2015). For example, hormones that circulate in the blood make

their way into the cell, where they can turn genes “on” and “off.” And the flow of hormones can be affected by environmental conditions such as light, day length, nutrition, and behavior. Numerous studies have shown that external events outside of the original cell and the person, as well as events inside the cell, can excite or inhibit gene expression (Lickliter & Honeycutt, 2015; Moore, 2015). Recent research has documented that factors such as stress, exercise, nutrition, respiration, radiation, temperature, and sleep can influence gene expression (Craft & others, 2014; Dedon & Begley, 2014; Donnelly & Storchova, 2015; Giles & others, 2016; Lindholm & others, 2014; Ma & others, 2015; McInnis & others, 2015; Mychasiuk, Muhammad, & Kolb, 2016; Turecki & Meaney, 2016). For example, one study revealed that an increase in the concentration of stress hormones such as cortisol produced a fivefold increase in DNA damage (Flint & others, 2007). Another study also found that exposure to radiation changed the rate of DNA synthesis in cells (Lee & others, 2011). And recent research indicates that sleep deprivation can affect gene expression in negative ways such as increased inflammation, expression of stress-related genes, and impairment of protein functioning (da Costa Souza & Ribeiro, 2015).

Genes and Chromosomes Genes are not only collaborative; they are enduring. How do they get passed from generation to generation and end up in all of the trillion cells in the body? Three processes are central to this story: mitosis, meiosis, and fertilization.

Mitosis, Meiosis, and Fertilization All cells in your body, except the sperm and egg, have 46 chromosomes arranged in 23 pairs. These cells reproduce through a process called mitosis.During mitosis, the cell’s nucleus—including the chromosomes—duplicates itself and the cell divides. Two new cells are formed, each containing the same DNA as the original cell, arranged in the same 23 pairs of chromosomes. However, a different type of cell division—meiosis—forms eggs and sperm (which also are called gametes). During meiosis, a cell of the testes (in men) or ovaries (in women) duplicates its chromosomes but then divides twice, thus forming four cells, each of which has only half of the genetic material of the parent cell (Johnson, 2017). By the end of meiosis, each egg or sperm has 23 unpaired chromosomes. During fertilization, an egg and a sperm fuse to create a single cell, called a zygote. In the zygote, the 23 unpaired chromosomes from the egg and the 23 unpaired chromosomes from the sperm combine to form one set of 23 paired chromosomes—one chromosome of each pair from the mother’s egg and the other from the father’s sperm. In this manner, each parent contributes half of the offspring’s genetic material. Page 41

Figure 3 shows 23 paired chromosomes of a male and a female. The members of each pair of chromosomes are both similar and different: Each chromosome in the pair contains varying forms of the same genes, at the same location on the chromosome. A gene that influences hair color, for example, is located on both members of one pair of chromosomes, at the same location on each. However, one of those chromosomes might

carry the gene associated with blond hair; the other might carry the gene associated with brown hair.

Figure 3 The Genetic Difference Between Males and Females Set (a) shows the chromosome structure of a male, and set (b) shows the chromosome structure

of a female. The last pair of 23 pairs of chromosomes is in the bottom right corner of each set.

Notice that the Y chromosome of the male is smaller than the X chromosome of the female. To

obtain this kind of chromosomal picture, a cell is removed from a person’s body, usually from

the inside of the mouth. The chromosomes are stained by chemical treatment, magnified

extensively, and then photographed.© CMSP/Custom Medical Stock Photo-All rights reserved

Do you notice any obvious differences between the chromosomes of the male and those of the female in Figure 3? The difference lies in the 23rd pair. Ordinarily, in females this pair consists of two chromosomes called X chromosomes; in males the 23rd pair consists of an X chromosome and a Y chromosome. The presence of a Y chromosome is one factor that makes a person male rather than female.

Sources of Variability Combining the genes of two parents in their offspring increases genetic variability in the population, which is valuable for a species because it provides more characteristics on which natural selection can operate (Belk & Borden Maier, 2016; Simon, 2017). In fact, the human genetic process creates several important sources of variability. First, the chromosomes in the zygote are not exact copies of those in the mother’s ovaries and the father’s testes. During the formation of the sperm and egg in meiosis, the members of each pair of chromosomes are separated, but which chromosome in the pair goes to the gamete is a matter of chance. In addition, before the pairs separate, pieces of the two chromosomes in each pair are exchanged, creating a new combination of genes on each chromosome. Thus, when chromosomes from the mother’s egg and the father’s sperm are brought together in the zygote, the result is a truly unique combination of genes.

Another source of variability comes from DNA. Chance events, a mistake by the cellular machinery, or damage caused by an environmental agent such as radiation may produce a mutated gene, a permanently altered segment of DNA (Bauman, 2015; Freeman & others, 2017). Even when their genes are identical, however, as for the identical twins described at the beginning of the chapter, people vary. The difference betweengenotypes and phenotypes helps us understand this source of variability. All of a person’s genetic material makes up his or her genotype. There is increasing interest in studying susceptibility genes, those that make the individual more vulnerable to specific diseases or accelerated aging, and longevity genes, those that make the individual less vulnerable to certain diseases and more likely to live to an older age (Cho & Suh, 2016; Dong & others, 2015; Sutphin & Korstanje, 2016). These are aspects of the individual’s genotype. However, not all of the genetic material is apparent in an individual’s observed and measurable characteristics. A phenotype consists of observable characteristics, including physical characteristics (such as height, weight, and hair color) and psychological characteristics (such as personality and intelligence). For each genotype, a range of phenotypes can be expressed, providing another source of variability (Klug & others, 2016; Solomon & others, 2015). An individual can inherit the genetic potential to grow very large, for example, but good nutrition, among other things, will be essential to achieving that potential.

Page 42

Genetic Principles What determines how a genotype is expressed to create a particular phenotype? This question has not yet been fully answered (Moore, 2015). However, a number of genetic principles have been discovered, among them those of dominant and recessive genes, sex-linked genes, and polygenically determined characteristics.

Dominant and Recessive Genes In some cases, one gene of a pair always exerts its effects; in other words, it is dominant, overriding the potential influence of the other gene, which is called the recessive gene. This is the dominant-and-recessive genes principle. A recessive gene exerts its influence only if the two genes of a pair are both recessive. If you inherit a recessive gene for a trait from each of your parents, you will show the trait. If you inherit a recessive gene from only one parent, you may never know that you carry the gene. Brown hair, farsightedness, and dimples override blond hair, nearsightedness, and freckles in the world of dominant and recessive genes. Can two brown-haired parents have a blond- haired child? Yes, they can. Suppose that each parent has a dominant gene for brown hair and a recessive gene for blond hair. Since dominant genes override recessive genes, the parents have brown hair, but both are carriers of blondness and pass on their recessive genes for blond hair. With no dominant gene to override them, the recessive genes can make the child’s hair blond.

Sex-Linked Genes Most mutated genes are recessive. When a mutated gene is carried on the X chromosome, the result is called X-linked inheritance. It may have implications for males that differ greatly from those for females (Simon & others, 2016). Remember that males have only one X chromosome. Thus, if there is an absent or altered, disease-relevant gene on the X chromosome, males have no “backup” copy to counter the harmful gene and therefore may develop an X-linked disease. However, females have a second X chromosome, which is likely to be unchanged. As a result, they are not likely to have the X-linked disease. Thus, most individuals who have X-linked diseases are males. Females who have one abnormal copy of the gene on the X chromosome are known as carriers, and they usually do not show any signs of the X-linked disease. Fragile X syndrome, which we will discuss later in the chapter, is an example of X-linked inheritance (Karmiloff-Smith & others, 2016).

Polygenic Inheritance Genetic transmission is usually more complex than the simple examples we have examined thus far (Moore, 2015). Few characteristics reflect the influence of only a single gene or pair of genes. Most are determined by the interaction of many different genes; they are said to be polygenically determined. Even a simple characteristic such as height reflects the interaction of many genes as well as the influence of the environment. Most diseases, such as cancer and diabetes, develop as a consequence of complex gene interactions and environmental factors. The term gene-gene interaction is increasingly used to describe studies that focus on the interdependent process by which two or more genes influence characteristics, behavior, diseases, and development (Cho & Suh, 2016; Hodge, Hager, & Greenberg, 2016). For example, recent studies have documented gene-gene interaction in immune system functioning (Heinonen & others, 2015), asthma (Hua & others, 2016), alcoholism (Yokoyama & others, 2013), cancer (Wu & others, 2016), cardiovascular disease (Musameh & others, 2015), arthritis (Hohman & others, 2016), and Alzheimer disease (Ebbert & others, 2016).

Chromosome and Gene-Linked Abnormalities In some (relatively rare) cases, genetic inheritance involves an abnormality. Some of these abnormalities come from whole chromosomes that do not separate properly during meiosis. Others are produced by defective genes.

Page 43

Chromosome Abnormalities Sometimes a gamete is formed in which the combined sperm and ovum do not have their normal set of 23 chromosomes. The most notable examples involve Down syndrome and abnormalities of the sex chromosomes. Figure 4 describes some chromosome abnormalities, along with their treatment and incidence.

Name Description Treatment Incidence

Down syndrome

An extra chromosome causes mild

to severe intellectual disabilities

and physical abnormalities.

Surgery, early

intervention, infant

stimulation, and special

learning programs

1 in 1,900 births at age 20

1 in 300 births at age 35

1 in 30 births at age 45

Klinefelter

syndrome (XXY)

An extra X chromosome causes

physical abnormalities.

Hormone therapy can

be effective 1 in 1,000 male births

Fragile X

syndrome

An abnormality in the X

chromosome can cause intellectual

disabilities, learning disabilities, or

short attention span.

Special education,

speech and language

therapy

More common in males

than in females

Turner syndrome

(XO)

A missing X chromosome in females

can cause intellectual disabilities

and sexual underdevelopment.

Hormone therapy in

childhood and puberty 1 in 2,500 female births

XYY syndrome

An extra Y chromosome can cause

above-average height.

No special treatment

required 1 in 1,000 male births

Figure 4 Some Chromosome Abnormalities The treatments for these abnormalities do not necessarily erase the problem but may improve

the individual’s adaptive behavior and quality of life.

Down Syndrome Down syndrome is one of the most common genetically linked causes of intellectual disability; it is also characterized by certain physical features (Lewanda & others, 2016). An individual with Down syndrome has a round face, a flattened skull, an extra fold of skin over the eyelids, a thickened tongue, short limbs, and retardation of motor and mental abilities. The syndrome is caused by the presence of an extra copy of chromosome 21. It is not known why the extra chromosome is present, but the health of the male sperm or female ovum may be involved. Down syndrome appears approximately once in every 700 live births. Women between the ages of 16 and 34 are less likely to give birth to a child with Down syndrome than are younger or older women. African American children are rarely born with Down syndrome.

These athletes, several of whom have Down syndrome, are participating in a Special Olympics

competition. Notice the distinctive facial features of the individuals with Down syndrome, such as a

round face and a flattened skull. What causes Down syndrome?© James Shaffer/PhotoEdit

Sex-Linked Chromosome Abnormalities Recall that a newborn normally has either an X and a Y chromosome, or two X chromosomes. Human embryos must possess at least one X chromosome to be viable. The most common sex-linked chromosome abnormalities involve the presence of an extra chromosome (either an X or a Y) or the absence of one X chromosome in females.

How Would You...?

As a social worker, how would you respond to a 33-year-old pregnant woman who is concerned

about the risk of giving birth to a baby with Down syndrome?

Klinefelter syndrome is a chromosomal disorder in which males have an extra X chromosome, making them XXY instead of XY. Males with this disorder have undeveloped testes, and they usually have enlarged breasts and become tall (Lunenfeld & others, 2015). Klinefelter syndrome occurs approximately once in every 1,000 live male births. Only 10 percent of individuals with Klinefelter syndrome are diagnosed before puberty, with the majority not identified until adulthood (Aksglaede & others, 2013). Page 44 Fragile X syndrome is a genetic disorder that results from an abnormality in the X chromosome, which becomes constricted and often breaks (Karmiloff-Smith & others, 2016). The outcome frequently takes the form of an intellectual disability, autism, a learning disability, or a short attention span (Hall & others, 2014). This disorder occurs more frequently in males than in females, possibly because the second X chromosome in females negates the effects of the other, abnormal X chromosome (McDuffie & others, 2015; Rocca & others, 2016). Turner syndrome is a chromosomal disorder in females in which either an X chromosome is missing, making the person XO instead of XX, or part of one X chromosome is deleted. Females with Turner syndrome are short in stature and have a webbed neck (Miguel-Neto & others, 2016; Vlatkovic & others, 2014). In some cases, they are infertile. They have difficulty in mathematics, but their verbal ability is often quite good. Turner syndrome occurs in approximately 1 of every 2,500 live female births. XYY syndrome is a chromosomal disorder in which the male has an extra Y chromosome (Lepage & others, 2014). Early interest in this syndrome focused on the belief that the extra Y chromosome found in some males contributed to aggression and violence. However, researchers subsequently found that XYY males are no more likely to commit crimes than are XY males (Witkin & others, 1976).

Gene-Linked Abnormalities Abnormalities can be produced not only by an abnormal number of chromosomes, but also by defective genes. Figure 5 describes some gene-linked abnormalities and outlines their treatment and incidence.

Name Description Treatment Incidence

Cystic fibrosis

Glandular dysfunction that

interferes with mucus

production; breathing and

digestion are hampered,

resulting in a shortened life

span.

Physical and oxygen therapy,

synthetic enzymes, and

antibiotics; most individuals live

to middle age. 1 in 2,000 births

Diabetes

Body does not produce

enough insulin, which causes

abnormal metabolism of

sugar.

Early onset can be fatal unless

treated with insulin. 1 in 2,500 births

Hemophilia

Delayed blood clotting causes

internal and external bleeding.

Blood transfusions/injections can

reduce or prevent damage due

to internal bleeding. 1 in 10,000 males

Huntington

disease

Central nervous system

deteriorates, producing

problems in muscle

coordination and mental

deterioration.

Does not usually appear until age

35 or older; death likely 10 to 20

years after symptoms appear. 1 in 20,000 births

Phenylketonuria

(PKU)

Metabolic disorder that, left

untreated, causes intellectual

disability.

Special diet can result in average

intelligence and normal life span.

1 in 10,000 to 1 in

20,000 births

Sickle-cell

anemia

Blood disorder that limits the

body’s oxygen supply; it can

cause joint swelling, as well as

heart and kidney failure.

Penicillin, medication for pain,

antibiotics, and blood

transfusions.

1 in 400 African

American children

(lower among other

groups)

Spina bifida

Neural tube disorder that

causes brain and spine

abnormalities.

Corrective surgery at birth,

orthopedic devices, and

physical/medical therapy. 2 in 1,000 births

Tay-Sachs

disease

Deceleration of mental and

physical development caused

by an accumulation of lipids in

the nervous system.

Medication and special diet are

used, but death is likely by 5

years of age.

1 in 30 American Jews

is a carrier.

Figure 5 Some Gene-Linked Abnormalities

Phenylketonuria (PKU) is a genetic disorder in which the individual cannot properly metabolize phenylalanine, an amino acid that naturally occurs in many food sources. It results from a recessive gene and occurs about once in every 10,000 to 20,000 live births. Today, phenylketonuria is easily detected in infancy, and it is treated by a diet that prevents an excess accumulation of phenylalanine (Rohde & others, 2014). If phenylketonuria is left untreated, however, excess phenylalanine Page 45 builds up in

the child, producing intellectual disability and hyperactivity. Phenylketonuria accounts for approximately 1 percent of individuals who are institutionalized for intellectual disabilities, and it occurs primarily in Whites.

How Would You...?

As a health-care professional, how would you explain the heredity-environment interaction to

new parents who are upset when they discover that their child has a treatable genetic defect? Sickle-cell anemia, which occurs most often in African Americans, is a genetic disorder that impairs functioning of the body’s red blood cells. Red blood cells, which carry oxygen to the body’s other cells, are usually shaped like a disk. In sickle-cell anemia, a recessive gene causes the red blood cell to become a hook-shaped “sickle” that cannot carry oxygen properly and dies quickly. As a result, the body’s cells do not receive adequate oxygen, causing anemia and early death (Derebail & others, 2014). About 1 in 400 African American babies is affected by sickle-cell anemia. One in 10 African Americans is a carrier, as is 1 in 20 Latin Americans. Recent research strongly supports the use of hydroxyurea therapy for infants with sickle-cell anemia beginning at 9 months of age (Yawn & John-Sowah, 2015). Other diseases that result from genetic abnormalities include cystic fibrosis, some forms of diabetes, hemophilia, Huntington disease, Alzheimer disease, spina bifida, and Tay- Sachs disease. Someday, scientists may be able to determine why these and other genetic abnormalities occur and discover how to cure them (Capurro & others, 2015; Tai & others, 2015; Wang & others, 2016; Williams & others, 2016).

Genetic counselors, usually physicians or biologists who are well-versed in the field of medical genetics, may specialize in providing information to individuals who are at risk of giving birth to children with the kinds of genetic abnormalities just described (Stilwell, 2016). They can evaluate the degree of risk involved and offer helpful strategies for offsetting some of the effects of these diseases (Paneque, Sequeiros, & Skirton, 2015; Redlinger-Grosse & others, 2016). To read about the career and work of a genetic counselor, see Careers in Life-Span Development.

Careers in life-span development

Holly Ishmael, Genetic Counselor Holly Ishmael is a genetic counselor at Children’s Mercy Hospital in Kansas City. She obtained an undergraduate degree in psychology and then a master’s degree in genetic counseling from Sarah Lawrence College.

Genetic counselors work as members of a health-care team, providing information and support to families with birth defects or genetic disorders. They identify families at risk by analyzing inheritance patterns and explore options with the family. Some genetic counselors, like Holly, become specialists in prenatal and pediatric genetics; others might specialize in cancer genetics or psychiatric genetic disorders.

Holly says, “Genetic counseling is a perfect combination for people who want to do something science-oriented, but need human contact and don’t want to spend all of their time in a lab or have their nose in a book” (Rizzo, 1999, p. 3).

Genetic counselors hold specialized graduate degrees in the areas of medical genetics and counseling. They enter graduate school with undergraduate backgrounds from a variety of disciplines, including biology, genetics, psychology, public health, and social work. There are approximately 30 graduate genetic counseling programs in the United States. If you are interested in this profession, you can obtain further information from the National Society of Genetic Counselors at www.nsgc.org.

Holly Ishmael (left) in a genetic counseling session.© Holly Ishmael Welsh

Prenatal Development We turn now to a description of how the process of development unfolds from its earliest moment—the moment of conception—when two parental cells, with their unique genetic contributions, merge to create a new individual.

Conception occurs when a single sperm cell from a male unites with an ovum (egg) in a female’s fallopian tube in a process called fertilization. Over the next few months the genetic code discussed earlier directs a series of changes in the fertilized egg, but many events and hazards will influence how that egg develops and becomes a person.

The Course of Prenatal Development Prenatal development lasts approximately 266 days, beginning with fertilization and ending with birth. Pregnancy can be divided into three periods: germinal, embryonic, and fetal.

The Germinal Period The germinal period is the period of prenatal development that takes place in the first two weeks after conception. It includes the creation of the fertilized egg (the zygote), cell division, and the attachment of the multicellular organism to the uterine wall. Rapid cell division by the zygote begins the germinal period. (Recall from earlier in the chapter that this cell division occurs through a process called mitosis.) Within one week after conception, the differentiation of Page 50these cells—their specialization for different tasks—has already begun. At this stage the organism, now called the blastocyst, consists of a hollow ball of cells that will eventually develop into the embryo, and the trophoblast, an outer layer of cells that later provides nutrition and support for the embryo. Implantation, the embedding of the blastocyst in the uterine wall, takes place during the second week after conception. Figure 7 summarizes these significant developments in the germinal period.

Figure 7 Major Developments in the Germinal Period

The Embryonic Period The embryonic period is the period of prenatal development that occurs from two to eight weeks after conception. During the embryonic period, the rate of cell differentiation intensifies, support systems for cells form, and organs develop. The mass of cells is now called an embryo, and three layers of cells form. The embryo’s endoderm is the inner layer of cells, which will develop into the digestive and respiratory systems. The ectoderm is the outermost layer, which will become the nervous system, sensory receptors (ears, nose, and eyes, for example), and skin parts (hair and nails, for example). The mesoderm is the middle layer, which will become the circulatory system, bones, muscles, excretory system, and reproductive system. Every body part eventually develops from these three layers. The endoderm primarily produces internal body parts, the mesoderm primarily produces parts that surround the internal areas, and the ectoderm primarily produces surface parts. Organogenesis is the name given to the process of organ formation during the first two months of prenatal development. While they are being formed, the organs are especially vulnerable to environmental influences.

How Would You...?

As a human development and family studies professional, how would you characterize the

greatest risks at each period of prenatal development? As the embryo’s three layers form, life-support systems for the embryo develop rapidly. These systems include the amnion, the umbilical cord (both of which develop from the fertilized egg, not the mother’s body), and the placenta. The amnion is like a bag or an envelope; it contains a clear fluid in which the developing embryo floats. The amniotic fluid provides an environment that is temperature- and humidity-controlled, as well as shockproof. The umbilical cord, which typically contains two arteries and one vein, connects the baby to the placenta. The placenta consists of a disk-shaped group of tissues in which small blood vessels from the mother and the offspring intertwine but do not join. Page 51

Very small molecules—oxygen, water, salt, and nutrients from the mother’s blood, as well as carbon dioxide and digestive wastes from the baby’s blood—pass back and forth between the mother and the embryo or fetus. Large molecules cannot pass through the placental wall; these include red blood cells and some harmful substances, such as most bacteria, maternal wastes, and hormones (Holme & others, 2015; Pfeifer & Bunders, 2016). Virtually any drug or chemical substance a pregnant woman ingests can cross the placenta to some degree, unless it is metabolized or altered during passage, or is too large (Burton & Jauniaux, 2015).

A recent study confirmed that ethanol crosses the human placenta and primarily reflects maternal alcohol use (Matlow & others, 2013). Another study revealed that cigarette smoke weakened and increased the oxidative stress of fetal membranes from which the placenta develops (Menon & others, 2011). The stress hormone cortisol also can cross the placenta (Parrott & others, 2014). The mechanisms that govern the transfer of substances across the placental barrier are complex and not yet entirely understood (Kohan-Ghadr & others, 2016; Lecarpentier & others, 2016; Mandelbrot & others, 2015).

The Fetal Period The fetal period, which lasts about seven months, is the prenatal period that extends from two months after conception until birth in typical pregnancies. Growth and development continue their dramatic course during this time. Three months after conception, the fetus is about 3 inches long and weighs about 1 ounce. It has become active, moving its arms and legs, opening and closing its mouth, and moving its head. The face, forehead, eyelids, nose, and chin are distinguishable, as are the upper arms, lower arms, hands, and lower limbs. In most cases, the genitals can be identified as male or female. By the end of the fourth month of pregnancy, the fetus has grown to 6 inches in length and weighs 4 to 7 ounces. At this time, a growth spurt occurs in the body’s lower parts. For the first time, the mother can feel arm and leg movements. By the end of the fifth month, the fetus is about 12 inches long and weighs close to a pound. Structures of the skin have formed—including toenails and fingernails. The fetus is more active, showing a preference for a particular position in the womb. By the end of the sixth month, the fetus is about 14 inches long and has gained another 6 to 12 ounces.

The eyes and eyelids are completely formed, and a fine layer of hair covers the head. A grasping reflex is present and irregular breathing movements occur.

As early as six months of pregnancy (about 24 to 25 weeks after conception), the fetus for the first time has a chance of surviving outside the womb—that is, it is viable. Infants that are born early, or between 24 and 37 weeks of pregnancy, usually need help breathing because their lungs are not yet fully mature. By the end of the seventh month, the fetus is about 16 inches long and weighs about 3 pounds. During the last two months of prenatal development, fatty tissues develop and the functioning of various organ systems—heart and kidneys, for example—steps up. During the eighth and ninth months, the fetus grows longer and gains substantial weight— about 4 more pounds. At birth, the average American baby weighs 7½ pounds and is about 20 inches long. In addition to describing prenatal development in terms of germinal, embryonic, and fetal periods, prenatal development also can be divided into equal three-month periods called trimesters. Figure 8 gives an overview of the main events during each trimester. Remember that the three trimesters are not the same as the three prenatal periods we have discussed. The germinal and embryonic periods occur in the first trimester. The fetal period begins toward the end of the first trimester and continues through the second and third trimesters. First trimester (first 3 months)

Conception to 4 weeks • Is less than 1/10 inch long • Beginning development of spinal cord, nervous system, gastrointestinal system, heart, and lungs

• Amniotic sac envelops the preliminary tissues of entire body

• Is called a “zygote,” then a “blastocyst”

8 weeks • Is just over 1 inch long

• Face is forming with rudimentary eyes, ears, mouth, and tooth buds

• Arms and legs are moving • Brain is forming

• Fetal heartbeat is detectable with ultrasound

• Is called an “embryo”

12 weeks • Is about 3 inches long and weighs about 1 ounce

• Can move arms, legs, fingers, and toes

• Fingerprints are present • Can smile, frown, suck, and swallow

• Sex is distinguishable

• Can urinate

• Is called a “fetus”

Second trimester (middle 3 months)

16 weeks • Is about 6 inches long and weighs about 4 to 7 ounces

• Heartbeat is strong

• Skin is thin, transparent

• Downy hair (lanugo) covers body

• Fingernails and toenails are forming

• Has coordinated movements; is able to roll over in amniotic fluid

20 weeks • Is about 12 inches long and weighs close to 1 pound

• Heartbeat is audible with ordinary stethoscope

• Sucks thumb

• Hiccups

• Hair, eyelashes, eyebrows are present

24 weeks • Is about 14 inches long and weighs about 1 to 1½ pounds

• Skin is wrinkled and covered with protective coating (vernix caseosa)

• Eyes are open

• Waste matter is collected in bowel

• Has strong grip

Third trimester (last 3 months)

28 weeks • Is about 16 inches long and weighs about 3 pounds

• Is adding body fat

• Is very active

• Rudimentary breathing movements are present

32 weeks • Is 16½ to 18 inches long and weighs 4 to 5 pounds

• Has periods of sleep and wakefulness

• Responds to sounds

• May assume the birth position

• Bones of head are soft and flexible

• Iron is being stored in liver

36 to 38 weeks • Is 19 to 20 inches long and weighs 6 to 7½ pounds

• Skin is less wrinkled

• Vernix caseosa is thick

• Lanugo is mostly gone

• Is less active

• Is gaining immunities from mother

Figure 8 Growth and Development in the Three Trimesters of Prenatal Development(Top) ©

David Spears/PhotoTake, Inc.; (middle) © Neil Bromhall/Science Source; (bottom) © Brand X Pictures/PunchStock RF

The Brain One of the most remarkable aspects of the prenatal period is the development of the brain (Bale, 2015; Stiles & others, 2015). By the time babies are born, they have approximately 100 billion neurons, or nerve cells, which handle information processing at the cellular level in the brain. Page 52 During prenatal development, neurons move to

specific locations and start to become connected. The basic architecture of the human brain is assembled during the first two trimesters of prenatal development. In typical development, the third trimester of prenatal development and the first two years of postnatal life are characterized by connectivity and functioning of neurons (Nelson, 2012). Four important phases of the brain’s development during the prenatal period involve (1) formation of the neural tube; (2) neurogenesis; (3) neural migration, and (4) neural connectivity.

As the human embryo develops inside its mother’s womb, the nervous system begins forming as a long, hollow tube located on the embryo’s back. This pear-shaped neural tube, which forms at about 18 to 24 days after conception, develops out of the ectoderm. The tube closes at the top and bottom ends at about 24 days after conception. Figure 9 shows that the nervous system still has a tubular appearance 6 weeks after conception.

Figure 9 Early Formation of the Nervous System

The photograph shows the primitive, tubular appearance of the nervous system at six weeks in the

human embryo.© Claude Edelmann/Science Source

Two birth defects related to a failure of the neural tube to close are anencephaly and spina bifida. When a fetus has anencephaly (that is, when the head end of the neural tube fails to close), the highest regions of the brain fail to develop and the baby dies in the womb, during childbirth, or shortly after birth (Steric & others, 2015). Spina bifida, Page 53an incomplete development of the spinal cord, results in varying degrees of paralysis of the lower limbs. Individuals with spina bifida usually need assistive devices such as crutches, braces, or wheelchairs. Both maternal diabetes and obesity also place the fetus at risk for developing neural tube defects (McMahon & others, 2013; Yu, Wu, & Yang, 2016). Further, a recent study revealed that a high level of maternal stress during pregnancy was associated with neural tube defects in offspring (Li & others, 2013). A strategy that can help to prevent neural tube defects is for women to take adequate amounts of the B vitamin folic acid (Bergman & others, 2016). A recent large-scale study in Brazil found that when flour was fortified with folic acid it produced a significant reduction in neural tube defects (Santos & others, 2016). In a normal pregnancy, once the neural tube has closed, a massive proliferation of new immature neurons begins to take place about the fifth prenatal week and continues throughout the remainder of the prenatal period. The production of new neurons is called neurogenesis. At the peak of neurogenesis, it is estimated that as many as 200,000 neurons are being generated every minute.

At approximately 6 to 24 weeks after conception, neuronal migration occurs (Nelson, 2012). Cells begin moving outward from their point of origin to their appropriate locations and creating the different levels, structures, and regions of the brain (Miyazaki, Song, & Takahashi, 2016; Zeisel, 2011). Once a cell has migrated to its target destination, it must mature and develop a more complex structure. At about the 23rd prenatal week, connections between neurons begin to form, a process that continues postnatally (Kostovic, Judas, & Sedmak, 2011; Miller, Huppi, & Mallard, 2016). We will have much more to say about the structure of neurons, their connectivity, and the development of the infant brain.

Prenatal Tests Together with her doctor, a pregnant woman will decide the extent to which she should undergo prenatal testing. A number of tests can indicate whether a fetus is developing normally; these include ultrasound sonography, fetal MRI, chorionic villus sampling, amniocentesis, maternal blood screening, and noninvasive prenatal diagnosis. The decision to have a given test depends on several criteria, such as the mother’s age, medical history, and genetic risk factors.

Ultrasound Sonography An ultrasound test is generally performed 7 weeks into a pregnancy and at various times later in pregnancy. Ultrasound sonography is a noninvasive prenatal medical procedure in which high-frequency sound waves are directed into the pregnant woman’s abdomen (Goncalves, 2016; Li & others, 2015). The echo from the sounds is transformed into a visual representation of the fetus’s inner structures. This technique can detect many structural abnormalities in the fetus, including microencephaly, a form of intellectual disability involving an abnormally small brain; it can also give clues to the baby’s sex and indicate whether there is more than one fetus (Calvo-Garcia, 2016; Rink & Norton, 2016). A recent research review concluded that many aspects of the developing prenatal brain can be detected by ultrasound in the first trimester and that about 50 percent of spina bifida cases can be identified at this time, most of these being severe cases (Engels & others, 2016). There is virtually no risk to the woman or fetus in using ultrasound. Page 54

Chorionic Villus Sampling At some point between the 10th and 12th weeks of pregnancy, chorionic villus sampling may be used to screen for genetic defects and chromosome abnormalities. Chorionic villus sampling (CVS) is a prenatal medical procedure in which a tiny tissue sample from the placenta is removed and analyzed (Lankford & others, 2015; Monni & others, 2016). The results are available in about 10 days.

A 6-month-old poses with the ultrasound image taken four months into the baby’s prenatal

development. What is ultrasound sonography and what can it detect?© AJ Photo/BSIP/age fotostock

Amniocentesis Between the 15th and 18th weeks of pregnancy, amniocentesis may be performed. In this procedure, a sample of amniotic fluid is withdrawn by syringe and tested for chromosomal or metabolic disorders (Ekblad & others, 2015; Lehmann, 2016). The later in the pregnancy amniocentesis is performed, the better its diagnostic potential. However, the earlier it is performed, the more useful it is in deciding how to handle a pregnancy when the fetus is found to have a disorder. It may take two weeks for enough cells to grow so that amniocentesis test results can be obtained. Amniocentesis brings a small risk of miscarriage: about 1 woman in every 200 to 300 miscarries after amniocentesis.

Maternal Blood Screening During the 16th to 18th weeks of pregnancy, maternal blood screening may be performed. Maternal blood screening identifies pregnancies that have an elevated risk for birth defects such as spina bifida and Down syndrome (Charkiewicz & others, 2016; Cuckle & Maymon, 2016), as well as congenital heart disease risk for children (Sun & others, 2016). The current blood test is called the triple screen because it measures three substances in the mother’s blood. After an abnormal triple screen result, the next step is usually an ultrasound examination. If an ultrasound does not explain the abnormal triple screen results, amniocentesis typically is used.

Fetal MRI The development of brain-imaging techniques has led to increasing use of fetal MRI to diagnose fetal malformations (Gat & others, 2016; Sanz-Cortes & others, 2015; You & others, 2016) (see Figure 10). MRI, which stands for magnetic resonance imaging, uses a powerful magnet and radio images to generate detailed images of the body’s organs and structures. Currently, high-quality ultrasound is still the first choice in fetal screening, but fetal MRI can provide more detailed images than ultrasound (Wataganara & others, 2016). In many instances, ultrasound will indicate a possible abnormality and fetal MRI will then be used to obtain a clearer, more detailed image Page 55 (Milani & others, 2015; Tee & others, 2016). Among the fetal

malformations that fetal MRI may be able to detect better than ultrasound sonography are certain abnormalities of the central nervous system, chest, gastrointestinal tract, genital/urinary organs, and placenta (Malinger & Lerman-Sagie, 2015). In a recent research review, it was concluded that fetal MRI often does not provide good results in the first trimester of pregnancy because of small fetal structures and movement artifacts (Wataganara & others, 2016). Also, in this review, it was argued that fetal MRI can be especially beneficial in assessing central nervous system abnormalities in the third trimester of pregnancy.

Figure 10 A Fetal MRI

Increasingly, MRI is being used to diagnose fetal malformations.© Du Cane Medical Imaging Ltd/Science Source

Fetal Sex Determination Chorionic villus sampling has often been used to determine the sex of the fetus at some point between 11 and 13 weeks of gestation. Also, in a recent study, ultrasound accurately identified the sex of the fetus between 11 and 13 weeks of gestation (Manzanares & others, 2016). Recently, though, some noninvasive techniques, such as

cell-free DNA analysis in blood plasma, have been able to detect the sex of the fetus at an earlier point (Breveglieri & others, 2016; Koumbaris & others, 2016; Moise & others, 2013). A meta-analysis of studies confirmed that a baby’s sex can be detected as early as 7 weeks into pregnancy (Devaney & others, 2011). Being able to detect an offspring’s sex as well as the presence of various diseases and defects at such an early stage raises ethical concerns about couples’ motivation to terminate a pregnancy (Browne, 2016; Lewis & others, 2012).

Infertility and Reproductive Technology Recent advances in biological knowledge have also opened up many choices for infertile people (Asero & others, 2014). Approximately 10 to 15 percent of couples in the United States experience infertility, which is defined as the inability to conceive a child after 12 months of regular intercourse without contraception. The cause of infertility can rest with either the woman or the man, or both (Brazdova & others, 2016; Zhou & others, 2016). The woman may not be ovulating (releasing eggs to be fertilized); she may be producing abnormal ova; her fallopian tubes (by which ova normally reach the womb) may be blocked; or she may have a condition that prevents implantation of the embryo into the uterus. The man may produce too few sperm; the sperm may lack motility (the ability to move adequately); or he may have a blocked passageway (Takasaki & others, 2014).

How Would You...?

As a psychologist, how would you advise a 25-year-old mother who is concerned about the

possibility of birth defects but has no genetic history of these types of problems? Surgery can correct some causes of infertility; for others, hormone-based drugs may be effective. Of the 2 million U.S. couples who seek help for infertility every year, about 40,000 try assisted reproduction technologies. In vitro fertilization (IVF), the technique that produced the world’s first “test tube baby” in 1978, involves eggs and sperm being combined in a laboratory dish. If any eggs are successfully fertilized, one or more of the resulting fertilized eggs is transferred into the woman’s uterus. The creation of families by means of assisted reproduction techniques raises important questions about the physical and psychological consequences for children (March of Dimes, 2016). For example, one result of fertility treatments is an increase in multiple births (De Neubourg & others, 2016). Twenty-five to 30 percent of pregnancies achieved by fertility treatments—including in vitro fertilization—result in multiple births. Fertility drugs are more likely to produce multiple births than in vitro fertilization (March

of Dimes, 2016). Any multiple birth increases the likelihood that the babies will have life-threatening and costly problems, such as extremely low birth weight (March of Dimes, 2016).

Hazards to Prenatal Development For most babies, the course of prenatal development goes smoothly. Their mother’s womb protects them as they develop. Despite this protection, however, the environment can affect the embryo or fetus in many well-documented ways.

Page 56

General Principles A teratogen is any agent that can potentially cause a birth defect or negatively alter cognitive and behavioral outcomes. The field of study that investigates the causes of birth defects is called teratology (Eltonsy & others, 2016; Kaushik & others, 2016; Stancil & others, 2016). Teratogens include drugs, incompatible blood types, environmental pollutants, infectious diseases, nutritional deficiencies, maternal stress, advanced maternal and paternal age, and environmental pollutants. The dose, genetic susceptibility, and time of exposure to a particular teratogen influence both the severity of the damage to an embryo or fetus and the type of defect: (1) Dose— The dose effect is rather obvious—the greater the dose of an agent, such as a drug, the greater the effect. (2) Genetic susceptibility—The type or severity of abnormalities caused by a teratogen is linked to the genotype of the pregnant woman and the genotype of the embryo or fetus (de Planell-Saguer, Lovinsky-Desir, & Miller, 2014). (3) Time of exposure—Teratogens do more damage when they occur at some points in development than at others. The probability of a structural defect is greatest early in the embryonic period, when organs are being formed (Holmes, 2011). After organogenesis is complete, teratogens are less likely to cause anatomical defects. Instead, exposure during the fetal period is more likely to stunt growth or create problems in the way organs function. To examine some key teratogens and their effects, let’s begin with drugs.

Prescription and Nonprescription Drugs Prescription drugs that can function as teratogens include antibiotics, such as streptomycin and tetracycline; some antidepressants; certain hormones, such as progestin and synthetic estrogen; and isotretinoin (often prescribed for acne) (Gonzalez- Echavarri & others, 2015). In a recent study, isotretinoin was the fourth most common drug given to female adolescents who were seeking contraception advice from a physician (Stancil & others, 2016). However, physicians did not give the adolescent girls adequate information about the negative effects of isotretinoin on offspring if the girls become pregnant. In a recent review of teratogens that should never be taken during the first trimester of pregnancy, isotreninoin was on the prohibited list (Eltonsy & others, 2016). Nonprescription drugs that can be harmful include diet pills and high doses of aspirin.

Psychoactive Drugs Psychoactive drugs act on the nervous system to alter states of consciousness, modify perceptions, and change moods. Examples include caffeine, alcohol, and nicotine, as well as illegal drugs such as cocaine, marijuana, and heroin. Caffeine People often consume caffeine by drinking coffee, tea, or colas, or by eating chocolate. Research has been mixed on the effects of caffeine intake by pregnant women on the fetus (Chen & others, 2016; Hahn & others, 2015; Sengpiel & others, 2013). However, the influence of increased consumption of energy drinks that typically have extremely high levels of caffeine on the development of offspring has not yet been studied. The U.S. Food and Drug Administration recommends that pregnant women either not consume caffeine or consume it only sparingly. Alcohol Heavy drinking by pregnant women can be devastating to offspring (Alexander, Dasinger, & Intapad, 2015; Valenzuela & others, 2016). Fetal alcohol spectrum disorders (FASD) are a cluster of abnormalities and problems that appear in the offspring of mothers who drink alcohol heavily during pregnancy (Coles & others, 2016; Roozen & others, 2016). The abnormalities include facial deformities and defective limbs, face, and heart (Arnold & others, 2013; Cook & others, 2016). Most children with FASD have learning problems, and many are below average in intelligence; some have an intellectual disability (Harper & others, 2014; Khoury & Milligan, 2016). A recent study revealed that children with FASD have deficiencies in the brain pathways involved in working memory (Diwadkar & others, 2012). A recent research review concluded that FASD is linked Page 57to a lower level of executive function in children, especially in planning (Kingdon, Cardoso, & McGrath, 2016). And in a recent study, FASD was associated with both externalized and internalized behavior problems in childhood (Tsang & others, 2016). Also, in a recent study in the United Kingdom, the life expectancy of individuals with FASD was only 34 years of age, about 42 percent of the life expectancy of the general population (Thanh & Jonsson, 2016). In this study, the most common causes of death among individuals with FASD were suicide (15 percent), accidents (14 percent), and poisoning by illegal drugs or alcohol (7 percent). Although mothers of FASD infants are heavy drinkers, many mothers who are heavy drinkers may not have children with FASD or may have one child with FASD and other children who do not have it. What are some guidelines for alcohol use during pregnancy? Even drinking just one or two servings of beer or wine or one serving of hard liquor a few days a week can have negative effects on the fetus, although it is generally agreed that this level of alcohol use will not cause fetal alcohol spectrum disorders (Valenzeula & others, 2012). The U.S. Surgeon General recommends that no alcohol be consumed during pregnancy, as does the French Alcohol Society (Rolland & others, 2016). And research suggests that it may not be wise to consume alcohol at the time of conception. One study revealed that intakes of alcohol by both men and women during the weeks of conception increased the risk of early pregnancy loss (Henriksen & others, 2004).

Fetal alcohol spectrum disorders (FASD) are

characterized by a number of physical abnormalities and learning problems. Notice the wide-set eyes,

flat cheekbones, and thin upper lip in this child with FASD.© Streissguth, AP, Landesman-Dwyer S, Martin, JC, & Smith, DW (1980). Teratogenic effects of alcohol in humans and laboratory animals. Science, 209, 353–361.

However, in Great Britain, the National Institutes of Care and Health Excellence have concluded that consuming one to two drinks not more than twice a week is safe during pregnancy (O’Keeffe, Greene, & Kearney, 2014). Also, a recent study of more than 7,000 7-year-olds found that children born to mothers who were light drinkers during pregnancy (up to two drinks per week) did not show more developmental problems than children born to non-drinking mothers (Kelly & others, 2013).

Nicotine Cigarette smoking by pregnant women can also adversely influence prenatal development, birth, and postnatal development (Ekblad, Korkeila, & Lehtonen, 2015; Palmer & others, 2016). Preterm births and low birth weights, fetal and neonatal deaths, respiratory problems, sudden infant death syndrome (SIDS, also known as crib death), and cardiovascular problems are all more common among the offspring of mothers who smoked during pregnancy (Grabenhenrich & others, 2014; Zhang & others, 2016). Prenatal smoking has been implicated in as many as 25 percent of infants being born with a low birth weight (Brown & Graves, 2013).

Researchers also have found that maternal smoking during pregnancy is a risk factor for the development of attention deficit hyperactivity disorder in children (Knopik & others, 2016). And in a recent study, maternal cigarette smoking during pregnancy was linked with offspring being more likely to smoke cigarettes at 16 years of age (De Genna & others, 2016). Further, a recent study found that maternal smoking during pregnancy was associated with increased risk of asthma and wheezing of offspring during adolescence (Hollams & others, 2014). And in a recent research review, it was concluded that maternal cigarette use during pregnancy is linked to alterations in a number of neurotransmitters in offspring, including serotonin and dopamine, as well as elevated blood pressure in offspring when they are adults (Suter & others, 2015). Researchers have documented that environmental tobacco smoke is linked to negative outcomes for offspring (Vardavas & others, 2016). In one study, environmental tobacco smoke led to an increased risk of low birth weight in offspring (Salama & others, 2013) and to diminished ovarian functioning in female offspring (Kilic & others, 2012). Also, one study revealed that environmental tobacco smoke was associated with 114 deregulations, especially those involving immune functioning, in the fetal cells of offspring (Votavova & others, 2012). Another recent study found that maternal exposure to environmental tobacco smoke during prenatal development increased the risk of stillbirth (Varner & others, 2014).

This baby was exposed to cocaine prenatally. What are some of

the possible effects on development of being exposed to cocaine prenatally?© Chuck Nacke/Alamy

Page 58

A final point about nicotine use during pregnancy involves the recent dramatic increase in the use of e-cigarettes (Spindel & McEvoy, 2016). A recent study found that misconceptions about e-cigarettes were common among pregnant women (Mark & others, 2015). The most common reasons pregnant women gave for using e-cigarettes

were the perceptions that they are less harmful than regular cigarettes (74 percent) and that they promote smoking cessation (72 percent).

Cocaine Does cocaine use during pregnancy harm the developing embryo and fetus? A recent research study found that cocaine quickly crossed the placenta to reach the fetus (De Giovanni & Marchetti, 2012). The most consistent finding is that cocaine exposure during prenatal development is associated with reduced birth weight, length, and head circumference (Gouin & others, 2011). In other studies, prenatal cocaine exposure has been linked to lower arousal, less effective self-regulation, higher excitability, and lower quality of reflexes at 1 month of age (Ackerman, Riggins, & Black, 2010); impaired motor development at 2 years of age and a slower rate of growth through 10 years of age (Richardson, Goldschmidt, & Willford, 2008); impaired language development and information processing, including attention deficits (especially impulsivity) (Accornero & others, 2006; Richardson & others, 2011); attention deficit hyperactivity disorder (Richardson & others, 2016); increased behavioral problems, especially externalizing problems such as high rates of aggression, oppositional defiant disorder, and delinquency (Minnes & others, 2010; Richardson & others, 2011, 2016); posttraumatic stress disorder (PTSD) (Richardson & others, 2016), and increased likelihood of being in a special education program that involves support services (Levine & others, 2008). Some researchers argue that these findings should be interpreted cautiously (Accornero & others, 2006). Why? Because other factors in the lives of pregnant women who use cocaine (such as poverty, malnutrition, and other substance abuse) often cannot be ruled out as possible contributors to the problems found in their children (Hurt & others, 2005; Messiah & others, 2011). For example, cocaine users are more likely than nonusers to smoke cigarettes, use marijuana, drink alcohol, and take amphetamines.

How Would You...?

As a social worker, what advice would you offer to women in their childbearing years who

frequently abuse drugs and other psychoactive substances? Despite these cautions, the weight of research evidence indicates that children born to mothers who use cocaine are likely to have neurological, medical, and cognitive deficits (Cain, Bornick, & Whiteman, 2013; Field, 2007; Mayer & Zhang, 2009; Richardson & others, 2011, 2016). Cocaine use by pregnant women is never recommended.

Marijuana An increasing number of studies find that marijuana use by pregnant women has negative outcomes for offspring. In a recent meta-analysis, marijuana use during pregnancy was linked to offsprings’ low birth weight and a greater likelihood of being placed in a neonatal intensive care unit (NICU) (Gunn & others, 2016). A recent study also revealed that marijuana use by pregnant women was associated with stillbirth (Varner & others, 2014). Another study found that prenatal marijuana exposure was related to lower intelligence in children (Goldschmidt & others, 2008). And one study indicated that prenatal exposure to marijuana was linked to marijuana use at 14 years of age (Day, Goldschmidt, & Thomas, 2006). In sum, marijuana use is not recommended for pregnant women. Heroin It is well documented that infants whose mothers are addicted to heroin show several behavioral difficulties at birth (Lindsay & Burnett, 2013). The difficulties include withdrawal symptoms, such as tremors, irritability, abnormal crying, disturbed sleep, and impaired motor control. Many still show behavioral problems at their first birthday, and attention deficits may appear later in development. The most common Page 59treatment for heroin addiction, methadone, is associated with very severe withdrawal symptoms in newborns (Blandthorn, Forster, & Love, 2011). Increasingly, buprenorphine is being used to treat heroin use during pregnancy (Krans & others, 2016).

Environmental Hazards Many aspects of our modern industrial world can endanger the embryo or fetus. Some specific hazards to the embryo or fetus include radiation, toxic wastes, and other environmental pollutants (Dursun & others, 2016; Ornoy, Weinstein-Fudim, & Ergaz, 2015). X-ray radiation can affect the developing embryo or fetus, especially in the first several weeks after conception, when women do not yet know they are pregnant. Women and their physicians should weigh the risk of an X-ray when the woman is or might be pregnant (Rajaraman & others, 2011). However, a routine diagnostic X-ray of a body area other than the abdomen, with the woman’s abdomen protected by a lead apron, is generally considered safe (Brent, 2009, 2011).

Maternal Diseases Maternal diseases and infections can produce defects in offspring by crossing the placental barrier, or they can cause damage during birth (Brunell, 2014). Rubella (German measles) is one disease that can cause prenatal defects. In a recent research review, rubella exposure during pregnancy is most likely to cause impairments involving the cardiovascular system, the pulmonary system, and microcephaly (Yazigi & others, 2016). Women who plan to have children should have a blood test before they become pregnant to determine whether they are immune to the disease (Ogbuanu & others, 2014).

Syphilis (a sexually transmitted infection) is more damaging later in prenatal development—four months or more after conception. Damage includes eye lesions, which can cause blindness, and skin lesions (Braccio, Sharland, & Ladhani, 2016). Penicillin is the only known treatment for syphilis during pregnancy (Moline & Smith, 2016).

Another infection that has received widespread attention is genital herpes. Newborns contract this virus when they are delivered through the birth canal of a mother with genital herpes (Sampath, Maduro, & Schillinger, 2016). About one-third of babies delivered through an infected birth canal die; another one-fourth suffer brain damage. If an active case of genital herpes is detected in a pregnant woman close to her delivery date, a cesarean section can be performed (in which the infant is delivered through an incision in the mother’s abdomen) to keep the virus from infecting the newborn (Pinninti & Kimberlin, 2013).

AIDS is a sexually transmitted infection that is caused by the human immunodeficiency virus (HIV), which destroys the body’s immune system. A mother can infect her offspring with HIV/AIDS in three ways: (1) across the placenta during gestation, (2) through contact with maternal blood or fluids during delivery, and (3) through breast feeding. The transmission of AIDS through breast feeding is a particular problem in many developing countries. Babies born to HIV-infected mothers can be (1) infected and symptomatic (show HIV symptoms), (2) infected but asymptomatic (not show HIV symptoms), or (3) not infected at all. An infant who is infected and asymptomatic may still develop HIV symptoms up to 15 months of age. The more widespread disease of diabetes, characterized by high levels of sugar in the blood, also affects offspring (Bider-Canfield & others, 2016; Eriksson, 2016). Women who have gestational diabetes (a condition in which women without previously diagnosed diabetes develop high blood glucose levels during pregnancy) have an increased risk of having very large infants (weighing 10 pounds or more), and the infants themselves are at risk for diabetes (Mitanchez & others, 2015). Also, a recent research review concluded that pregestational diabetes increases the risk of fetal heart disease (Pauliks, 2015). Further, a recent study found that maternal pregnancy diabetes was linked to offspring having an increased risk for fatty liver disease at 18 years of age (Patel & others, 2016). And another recent study revealed that maternal pregnancy diabetes was associated with an increased risk of autism in offspring (Xiang & others, 2015). Page 60

Other Parental Factors So far we have discussed a number of drugs, environmental hazards, maternal diseases, and incompatible blood types that can harm the embryo or fetus. Now we will explore other characteristics of the mother and father that can affect prenatal and child development, including nutrition, age, and emotional states and stress.

Maternal Diet and Nutrition A developing embryo or fetus depends completely on its mother for nutrition, which comes from the mother’s blood. The nutritional status of the embryo or fetus is determined by the mother’s total caloric intake as well as her intake of proteins, vitamins, and minerals. Children born to malnourished mothers are more likely than other children to be malformed. Maternal obesity adversely affects pregnancy outcomes through increased rates of hypertension, diabetes, respiratory complications, and infections in the mother (Kominiarek & Chauhan, 2016; Ojha & others, 2015; Stang & Huffman, 2016). Research studies have found that maternal obesity is linked to an increase in stillbirth (Gardosi &

others, 2013), preterm birth (Cnattingius & others, 2013), and increased likelihood that the newborn will be placed in a neonatal intensive care unit (Minsart & others, 2013). A recent study revealed that at 14 weeks following conception fetuses of obese pregnant women had less efficient cardiovascular functioning (Ingul & others, 2016). Further, a longitudinal study revealed that obesity during pregnancy was associated with long- term cardiovascular morbidity in adults (Yaniv-Salem & others, 2016). Further, two recent research reviews concluded that maternal obesity during pregnancy is associated with an increased likelihood of offspring being obese in childhood and adulthood (Pinto Pereira & others, 2016; Santangeli, Sattar, & Huda, 2015). Management of obesity that includes weight loss and increased exercise prior to pregnancy is likely to benefit both the mother and the baby (Ingul & others, 2016).

Because the fetus depends entirely

on its mother for nutrition, it is important for the pregnant woman to have good nutritional habits. In

Kenya, this government clinic provides pregnant women with information about how their diet can

influence the health of their fetus and offspring. What might the information about diet be like?© Betty Press

One aspect of maternal nutrition that is important for normal prenatal development is folic acid, a B-complex vitamin (Atta & others, 2016). A study of more than 34,000 women found that taking folic acid either alone or as part of a multivitamin for at least one year prior to conceiving was linked with a 70 percent lower risk of delivering at 20 to 28 weeks and a 50 percent lower risk of delivering at 28 to 32 weeks (Bukowski & others, 2008). Another study revealed that toddlers of mothers who did not use folic acid supplements in the first trimester of pregnancy had more behavioral problems (Roza & others, 2010). Also, as indicated earlier in the chapter, lack of folic acid is related to neural tube defects in offspring (Chitayat & others, 2016; Kondo & others, 2015). The U.S. Department of Health and Human Services (2016) recommends that pregnant women consume a minimum of 400 micrograms of folic acid per day (about

twice the amount the average woman gets in one day). Orange juice and spinach are examples of foods that are rich in folic acid. Also, a recent research study in China found that folic acid supplementation during pregnancy reduced the risk of preterm birth (Liu & others, 2015). Fish is often recommended as part of a healthy diet and in general fish consumption during pregnancy has positive benefits for children’s development (Golding & others, 2016; Julvez & others, 2016). The Federal Drug Administration (FDA) (2016) recommends that pregnant women increase their consumption of fish especially because they contain vital Page 61nutrients such as omega-3 fatty acids, protein, vitamins, and minerals such as iron. However, pollution has made some kinds of fish a risky choice for pregnant women. Some fish contain high levels of mercury, which is released into the air both naturally and by industrial processes (Wells & others, 2011). Mercury that falls into the water can accumulate in large fish, such as shark, swordfish, king mackerel, and some species of large tuna (American Pregnancy Association, 2016; Mayo Clinic, 2016). Researchers have found that prenatal mercury exposure is linked to adverse outcomes, including miscarriage, preterm birth, and lower intelligence (Xue & others, 2007). Recently, the American Pregnancy Association (2016) revised its conclusions about fish consumption during pregnancy, although still recommending avoidance of high- mercury-content fish such tilefish from the Gulf of Mexico, swordfish, shark, and king mackerel. The association and the FDA now recommend that pregnant women increase their consumption of low-mercury-content fish such as salmon, shrimp, tilapia, and cod. Maternal Age When possible harmful effects on the fetus and infant are considered, two maternal age categories are of special interest: adolescence and 35 years and older (Ben David & others, 2016; de Jongh & others, 2015; Gockley & others, 2016; Kawakita & others, 2016; Tearne & others, 2016). The mortality rate of infants born to adolescent mothers is double that of infants born to mothers in their twenties. Adequate prenatal care decreases the probability that a child born to an adolescent girl will have physical problems. However, adolescents are the least likely of women in all age groups to obtain prenatal assistance from clinics and health services. Maternal age is also linked to the risk that a child will have Down syndrome (Ghosh & others, 2010; Rumi Kataguiri & others, 2014). A baby with Down syndrome rarely is born to a mother 16 to 34 years of age. However, when the mother reaches 40 years of age, the probability is slightly higher than 1 in 100 that a baby born to her will have Down syndrome, and by age 50 it is almost 1 in 10. When mothers are 35 years and older, risks also increase for low birth weight, preterm delivery, and fetal death (Koo & others, 2012). A recent Norwegian study found that maternal age of 30 years or older was linked to the same level of increased risk for fetal deaths as 25- to 29-year-old pregnant women who were overweight/obese or were smokers (Waldenstrom & others, 2014). Also, in two recent studies, very advanced maternal age (40 years and older) was linked to adverse perinatal outcomes, including spontaneous abortion, preterm birth, stillbirth, and fetal growth restriction (Traisrislip & Tongsong, 2015; Waldenstrom & others, 2015). We still have much to learn about the role of the mother’s age in pregnancy and childbirth. As women remain active, exercise regularly, and are careful about their nutrition, their reproductive systems may remain healthier at older ages than was thought possible in the past.

Emotional States and Stress When a pregnant woman experiences intense fears, anxieties, and other emotions or negative mood states, physiological changes occur that may affect her fetus. A mother’s stress may also influence the fetus indirectly by increasing the likelihood that the mother will engage in unhealthy behaviors such as taking drugs and receiving poor prenatal care.

How Would You...?

As a health-care professional, what advice would you give to an expectant mother who is

experiencing extreme psychological stress? High maternal anxiety and stress during pregnancy can have long-term consequences for the offspring (Bauer, Knapp, & Parsonage, 2016; Brunton, 2015; Dalke, Wentzel, & Kim, 2016; Fan & others, 2016). A recent study found that high levels of depression, anxiety, and stress during pregnancy were linked to internalizing problems in adolescence (Betts & others, 2014). A research review indicated that pregnant women with high levels of stress are at increased risk for having a child with emotional or cognitive problems, attention deficit hyperactivity disorder (ADHD), and language delay (Taige & others, 2007). Also, a large-scale study found that a higher level of maternal stress in the period immediately prior to conception posed a risk for infant mortality (Class & others, 2013). Another study revealed that maternal stressful life events prior to conception increased the risk of having a very low birth weight infant (Witt & others, 2014). Page 62

Might maternal depression also have an adverse effect on birth outcomes? A research review concluded that maternal depression is linked to preterm birth (Mparmpakas & others, 2013). And a recent study discovered that maternal depression during pregnancy was associated with low birth weight in full-term offspring (Chang & others, 2014). There is some concern about pregnant women taking antidepressant medication. For example, a recent research review concluded that antidepressant medication use during pregnancy is linked to slightly increased risks of cardiac malfunctions in the fetus and persistent pulmonary hypertension in the newborn (Pearlstein, 2015). Also, a recent study found that taking antidepressants early in pregnancy was linked to an increased risk of miscarriage (Almeida & others, 2016). Further, a recent study revealed that taking antidepressants in the second or third trimester of pregnancy was linked to an increased risk of autism spectrum disorders in children (Boukhris & others, 2016).

In one study, in China, the longer fathers smoked, the

higher the risk that their children would develop cancer (Ji & others, 1997). What are some other

paternal factors that can influence the development of the fetus and the child?©Ryan Pyle/Corbis/Getty Images

Paternal Factors So far, we have discussed how characteristics of the mother—such as drug use, disease, diet and nutrition, age, and emotional states—can influence prenatal development and the development of the child. Might there also be some paternal risk factors? Indeed, there are several. Men’s exposure to lead, radiation, certain pesticides, and petrochemicals may cause abnormalities in sperm that lead to miscarriage or diseases such as childhood cancer (Cordier, 2008). The father’s smoking during the mother’s pregnancy also can cause problems for the offspring (Agricola & others, 2016; Han & others, 2015). In one study, heavy paternal smoking was associated with an increased risk of early miscarriage (Venners & others, 2005). This negative outcome may be related to the mother’s exposure to secondhand smoke. And in a recent study, paternal smoking around the time of the child’s conception was linked to an increased risk of the child developing leukemia (Milne & others, 2012). Researchers have found that increasing paternal age decreases the success rate of in vitro fertilization and increases the risk of preterm birth (Sharma & others, 2015). Also, a research review concluded that there is an increased risk of spontaneous abortion, autism, and schizophrenic disorders when the father is 40 years of age and older (Reproductive Endocrinology and Infertility Committee & others, 2012). Another way that the father can influence prenatal and birth outcomes is through his relationship with the mother. By being supportive, helping with chores, and having a positive attitude toward the pregnancy, the father can improve the physical and psychological well-being of the mother. Negative behavior by the father also affects the mother: a recent study found that intimate partner violence increased the mother’s stress level (Fonseca-Machado Mde & others, 2015). Much of our discussion on prenatal development has focused on what can go wrong. Prospective parents should take steps to avoid the vulnerabilities to fetal development that we have described. But it is important to keep in mind that most of the time, prenatal development does not go awry and development occurs along a positive path.

Prenatal Care Although prenatal care varies enormously from one woman to another, it usually involves a defined schedule of visits for medical care, which typically includes screening for manageable conditions and treatable diseases that can affect the baby or the mother. In addition to medical care, prenatal programs often include comprehensive educational, social, and nutritional services (Kroll-Desrosiers & others, 2016). Information about pregnancy, labor, delivery, and caring for the newborn can be especially valuable for first-time mothers (McDonald & others, 2015). Prenatal care is also very important for women in poverty and immigrant women because it links them with Page 63other social services (Mazul, Salm Ward, & Ngui, 2016). A recent study found that adequacy of prenatal care was associated with very low birth weight (Xaverius & others, 2016).

The increasingly widespread

CenteringPregnancy program alters routine prenatal care by bringing women out of exam rooms and

into relationship-oriented groups.© MBI/Stockbroker/Alamy Stock Photo RF

An innovative program that is rapidly expanding in the United States is CenteringPregnancy (Barger, Faucher, & Murphy, 2015; DeCesare & Jackson, 2015; Liu & others, 2016). This program is relationship-centered and provides complete prenatal care in a group setting (Heberlein & others, 2016). It replaces traditional 15-minute physician visits with 90-minute peer group support sessions and self-examination led by a physician or certified nurse-midwife. Groups of up to 10 women (and often their partners) meet regularly beginning at 12 to 16 weeks of pregnancy. The sessions emphasize empowering women to play an active role in experiencing a positive pregnancy. Research has revealed that CenteringPregnancy group prenatal care is associated with a reduction in preterm birth (Novick & others, 2013), as well as reductions in low birth weight and placement in a neonatal intensive care unit (Gareau & others, 2016). In another recent study with adolescent mothers, CenteringPregnancy was successful in getting participants to attend meetings, have appropriate weight gain, increase the use of highly effective contraceptive methods, and increase breast feeding (Trotman & others, 2015).

Some prenatal programs for parents focus on home visitation (Issel & others, 2011). A recent study found that use of home visiting services was associated with reduced risk of low birth weight (Shah & Austin, 2014). Research evaluations indicate that the Nurse- Family Partnership created by David Olds and his colleagues (2004, 2007, 2014) is successful. The Nurse-Family Partnership involves home visits by trained nurses beginning in the second or third trimester of prenatal development. The extensive program consists of approximately 50 home visits beginning during the prenatal period and extending through the child’s first two years. Research has revealed that the Nurse- Family Partnership has numerous positive outcomes, including fewer pregnancies, better work circumstances, and stability in relationship partners for the mother, and improved academic success and social development for the child (Olds & others, 2004, 2007, 2014).

Exercise increasingly is recommended as part of a comprehensive prenatal care program (Barakat & others, 2015; Perales & others, 2016; Schmidt, Chari, & Davenport, 2016). Exercise during pregnancy helps prevent constipation, conditions the body, reduces excessive weight gain, and is associated with a more positive mental state, including a reduced level of depression (Marques & others, 2015; Shirazian & others, 2016). One study found that exercise during pregnancy improved mothers’ perception of their health (Barakat & others, 2011). Further, a recent study indicated that pregnant women who did not exercise three or more times a week were more likely to develop hypertension (Barakat & others, 2016). And in one study, following 12 weeks of twice- weekly yoga or massage therapy, both therapy groups had a greater decrease in depression, anxiety, and back and leg pain than a control group (Field & others, 2013). Also, a recent study revealed that yoga participation provided immediate stress reduction for pregnant women (Kusaka & others, 2016). And a recent study revealed that physical exercise during pregnancy reduced the risk of cesarean delivery (Domenjoz, Kayser, & Boulvain, 2014).

Birth and the Postpartum Period The long wait for the moment of birth is over, and the infant is about to appear. What happens during childbirth, and what can be done to make the experience a positive one?

Nature writes the basic script for how birth occurs, but parents make important choices about the conditions surrounding birth. We look first at the sequence of physical steps through which a child is born.

Page 64

The Birth Process The birth process occurs in three stages. It may take place in different contexts and in most cases involves one or more attendants.

After the long journey of prenatal development, birth takes place. During birth the baby is on a

threshold between two worlds. What are the characteristics of the three stages of birth?© Jonathan Nourok/Getty Images

Stages of Birth The first stage of the birth process is the longest. Uterine contractions are 15 to 20 minutes apart at the beginning and last up to a minute each. These contractions cause the woman’s cervix to stretch and open. As the first stage progresses, the contractions come closer together, occurring every two to five minutes. Their intensity increases. By the end of the first stage, contractions dilate the cervix to an opening of about 10 centimeters (4 inches) so that the baby can move from the uterus to the birth canal. For a woman having her first child, the first stage lasts an average of 6 to 12 hours; for subsequent children, this stage typically is much shorter. The second birth stage begins when the baby’s head starts to move through the cervix and the birth canal. It terminates when the baby completely emerges from the mother’s body. With each contraction, the mother bears down hard to push the baby out of her body. By the time the baby’s head is out of the mother’s body, the contractions come almost every minute and last for about a minute. This stage typically lasts approximately 45 minutes to an hour. Afterbirth is the third stage, during which the placenta, umbilical cord, and other membranes are detached and expelled. This final stage is the shortest of the three birth stages, lasting only minutes.

Childbirth Setting and Attendants In 2013 in the United States, 98.6 percent of births took place in hospitals (Martin & others, 2015). Of the 1.4 percent of births occurring outside of a hospital, approximately two-thirds took place in homes and almost 30 percent in free-standing birthing centers. The percentage of U.S. births at home is the highest since reporting of this context began in 1989. An increase in home births has occurred mainly among non-Latino White women, especially those who are older and married. For these non-Latino White women, two-thirds of their home births are attended by a midwife.

The person who helps a mother during birth varies across cultures. In U.S. hospitals, it has become the norm for fathers or birth coaches to be with the mother throughout labor and delivery. In the East African Nigoni culture, by contrast, men are completely excluded from the childbirth process. When a woman is ready to give birth, female relatives move into the woman’s hut and the husband leaves, taking his belongings (clothes, tools, weapons, and so on) with him. He is not permitted to return until after the baby is born. In some cultures, childbirth is an open, community affair. For example, in the Pukapukan culture in the Pacific Islands, women give birth in a shelter that is open to villagers, who may observe the birth.

Midwives Midwifery is a profession that provides health care to women during pregnancy, birth, and the postpartum period (Ekelin, Kvist, & Persson, 2016; Feijen-de Jong & others, 2015a, b; Reed, Rowe, & Barnes, 2016). Midwives also may give women information about reproductive health and annual gynecological examinations. They may refer women to general practitioners or obstetricians if a pregnant woman needs medical care beyond a midwife’s expertise and skill. Midwifery is practiced in most countries throughout the world (ten Hoope-Bender & others, 2016). In Holland, more than 40 percent of babies are delivered by midwives rather Page 65than by doctors. However, in 2013 in the United States only 7.8 percent of women who delivered a baby were attended by a midwife, a figure that was unchanged since 2000 (Martin & others, 2015). Nevertheless, the 7.8 percent figure for 2013 represents a substantial increase from less than 1 percent in 1975. A research review concluded that for low-risk women, midwife-led care was characterized by a reduction in procedures during labor and increased satisfaction with care (Sutcliffe & others, 2012). Also, in this study no adverse outcomes were found for midwife-led care compared with physician-led care. Doulas In some countries, a doula attends a childbearing woman. Doula is a Greek word that means “a woman who helps.” A doula is a caregiver who provides continuous physical, emotional, and educational support for the mother before, during, and after childbirth (Kozhimannil & others, 2016). Doulas remain with the parents throughout labor, assessing and responding to their needs. Researchers have found positive effects when a doula is present at the birth of a child (Ahlemeyer & Mahon, 2015; Zielinski, Brody, & Low, 2016). A recent study also revealed that for Medicaid recipients the odds of having a cesarean delivery were 41 percent lower for doula-supported births in the United States (Kozhimmanil & others, 2013). Thus, increasing doula-supported births could substantially lower the cost of a birth by reducing cesarean rates.

In the United States, most doulas work as independent providers hired by the expectant parents. Doulas typically function as part of a “birthing team,” serving as an adjunct to the midwife or the hospital’s obstetric staff.

Methods of Childbirth U.S. hospitals often allow the mother and her obstetrician a range of options regarding their method of delivery. Key choices involve the use of medication, whether to use any of a number of nonmedicated techniques to reduce pain, and when to have a cesarean delivery.

Medication Three basic kinds of drugs that are used for labor are analgesia, anesthesia, and oxytocin/Pitocin. Analgesia is used to relieve pain. Analgesics include tranquilizers, barbiturates, and narcotics such as Demerol. Anesthesia is used in late first-stage labor and during delivery to block sensation in an area of the body or to block consciousness. There is a trend toward not using general anesthesia, which blocks consciousness, in normal births because general anesthesia can be transmitted through the placenta to the fetus (Pennell & others, 2011). An epidural block is regional anesthesia that numbs the woman’s body from the waist down. Oxytocin is a hormone that promotes uterine contractions; a synthetic form called Pitocin™ is widely used to decrease the duration of the first stage of labor. The relative benefits and risks of administering synthetic forms of oxytocin during childbirth continue to be debated (Bell, Erickson, & Carter, 2014; Shiner, Many, & Maslovitz, 2016). Predicting how a drug will affect an individual woman and her fetus is difficult (Ansari & others, 2016). A particular drug might have only a minimal effect on one fetus yet have a much stronger effect on another. The drug’s dosage is also a factor. Stronger doses of tranquilizers and narcotics given to decrease the mother’s pain potentially have a more negative effect on the fetus than do mild doses. It is important for the mother to assess her level of pain and have a voice in deciding whether she should receive medication.

How Would You...?

As a health-care provider, how would you advise a woman in her first trimester about the options

available for her baby’s birth and for her own comfort during the process?

Natural and Prepared Childbirth For a brief time not long ago, the idea of avoiding all medication during childbirth gained favor in the United States. Instead, many women chose to reduce the pain of childbirth through techniques known as natural childbirth and prepared childbirth. Today, at least some medication is used in the typical childbirth, but elements of natural childbirth and prepared childbirth remain popular (Podgurski, 2016). Page 66

Natural childbirth is a childbirth method in which no drugs are given to relieve pain or assist in the birth process. The mother and her partner are taught to use breathing methods and relaxation techniques during delivery. French obstetrician Ferdinand Lamaze developed a method similar to natural childbirth that is known as prepared childbirth, or the Lamaze method. It includes a special breathing technique to control pushing in the final stages of labor, as well as more detailed education about anatomy and physiology. The Lamaze method has become very popular in the United States. The pregnant woman’s partner usually serves as a coach; the partner attends childbirth classes with her and helps her with her breathing and relaxation during delivery. In sum, proponents of current prepared childbirth methods conclude that when information and support are provided, women know how to give birth. Other Nonmedicated Techniques to Reduce Pain The effort to reduce stress and control pain during labor has recently led to an increase in the use of some older and some newer nonmedicated techniques (Henderson & others, 2014). These include waterbirth, massage, and acupuncture.

What characterizes the use of waterbirth in delivering a baby?© Daisy Smith/Alamy

Waterbirth involves giving birth in a tub of warm water. Some women go through labor in the water and get out for delivery; others remain in the water for delivery. The rationale for waterbirth is that the baby has been in an amniotic sac for many months and that delivery in a similar environment is likely to be less stressful for the baby and the mother (Kavosi & others, 2015; Taylor & others, 2016). An increasing number of studies are either showing no differences in neonatal and maternal outcomes for waterbirth and non-waterbirth deliveries or positive outcomes (Davies & others, 2015; Taylor & others, 2016). For example, a recent large-scale study of more than 16,000 waterbirth and non-waterbirth deliveries found fewer negative outcomes for the waterbirth newborns (Bovbjerg, Cheyney, & Everson, 2016). Further, a recent research review concluded that waterbirth is associated with high levels of maternal satisfaction with pain relief and the experience of childbirth (Nutter & others, 2015). Waterbirth has been practiced more often in European countries such as Switzerland and Sweden in recent decades than in the United States, but is increasingly being included in U.S. birth plans. Massage is increasingly used during pregnancy, labor, and delivery (Frawley & others, 2016; Vargens, Silva, & Progianti, 2013). Two research reviews concluded that massage therapy reduced pain during labor (Jones & others, 2012; Smith & others, 2012).

Acupuncture, the insertion of very fine needles into specific locations in the body, is used as a standard procedure to reduce the pain of childbirth in China, although it only recently has begun to be used for this purpose in the United States (Moleti, 2009; Smith, Armour, & Ee, 2016). Research indicates that acupuncture can have positive effects on labor and delivery (Akbarzadeh & others, 2015; Smith & others, 2011). For example, in a recent study acupuncture was successful in reducing labor pain 30 minutes after the intervention (Allameh, Tehrani, & Ghasemi, 2015).

Cesarean Delivery Normally, the baby’s head comes through the vagina first. But if the baby is in a breech position, its buttocks are the first part to emerge from the vagina. In 1 of every 25 deliveries, the baby’s head is still in the uterus when the rest of the body is out. Because breech births can cause respiratory problems, if the baby is in a breech position a surgical procedure known as a cesarean delivery is usually performed. In a cesarean delivery (or cesarean section), the baby is removed from the uterus through an incision made in the mother’s abdomen. The benefits and risks of cesarean deliveries Page 67continue to be debated (Furukawa, Sameshima, & Ikenoue, 2014). Some critics argue that far too many babies are delivered by cesarean section in the United States and around the world (Gibbons & others, 2012). The U.S. cesarean birth rate (38.7 percent) was essentially unchanged from 2010 through 2013 (Martin & others, 2015).

The Transition from Fetus to Newborn Much of our discussion of birth so far has focused on the mother. However, birth also involves considerable stress for the baby. If the delivery takes too long, the baby can develop anoxia, a condition in which the fetus or newborn has an insufficient supply of oxygen. Anoxia can cause brain damage.

The baby has considerable capacity to withstand the stress of birth. Large quantities of adrenaline and noradrenaline, hormones that protect the fetus in the event of oxygen deficiency, are secreted in the newborn’s body during the birth process.

Immediately after birth, the umbilical cord is cut and the baby is on its own. Before birth, oxygen came from the mother via the umbilical cord, but now the baby can breathe independently.

Almost immediately after birth, a newborn is taken to be weighed, cleaned up, and tested for signs of developmental problems that might require urgent attention. The Apgar Scale is widely used to assess the health of newborns at one and five minutes after birth. The Apgar Scale evaluates infants’ heart rate, respiratory effort, muscle tone, body color, and reflex irritability. An obstetrician or nurse does the evaluation and gives the newborn a score, or reading, of 0, 1, or 2 on each of these five health signs. A total score of 7 to 10 indicates that the newborn’s condition is good. A score of 5 indicates that there may be developmental difficulties. A score of 3 or below signals an emergency and warns that the baby might not survive. The Apgar Scale is especially good at assessing the newborn’s ability to respond to the stress of delivery and its new environment (Miyakoshi & others, 2013). It also identifies high-risk infants who need resuscitation. Recent studies have found that low Apgar scores are associated with long-term additional support needs in education and educational attainment (Tweed & others, 2016), risk of developmental vulnerability at 5 years of age (Razaz & others, 2016), and risk of developing ADHD (Hanc & others, 2016). Nurses often play important roles in the birth of a baby. To read about the work of a nurse who specializes in the care of women during labor and delivery, see Careers in Life-Span Development.

Careers in life-span development

Linda Pugh, Perinatal Nurse Perinatal nurses work with childbearing women to support health and growth during the childbearing experience. Linda Pugh, Ph.D., R.N.C., is a perinatal nurse on the faculty at The Johns Hopkins University School of Nursing. She is certified as an inpatient obstetric nurse and specializes in the care of women during labor and delivery. She teaches undergraduate and graduate students, educates professional nurses, and conducts research. In addition, Pugh consults with hospitals and organizations about women’s health issues and many of the topics we discuss in this chapter.

Her research interests include nursing interventions with low-income breast-feeding women, discovering ways to prevent and ameliorate fatigue during childbearing, and using breathing exercises during labor.

Linda Pugh (right) with a mother and her newborn.© Dr. Linda Pugh

Page 68

Low Birth Weight and Preterm Infants Three related conditions pose threats to many newborns: low birth weight, preterm birth, and being small for date. Low birth weight infants weigh less than 5 pounds at birth. Very low birth weight newborns weigh under 3 pounds, and extremely low birth weight newborns weigh under 2 pounds. Preterm infants are born three weeks or more before the pregnancy has reached its full term—in other words, 35 or fewer weeks after conception. Small for date infants (also called small for gestational age infants) have a birth weight that is below normal when the length of the pregnancy is considered. They weigh less than 90 percent of all babies of the same gestational age. Small for date infants may be preterm or full term. One study found that small for date infants have a 400 percent greater risk of death (Regev & others, 2003). In 2013, 11.4 percent of U.S. infants were born preterm—a 34 percent increase since the 1980s but a decrease of 1.4 percent since 2008 (Martin & others, 2015). The increase in preterm birth is likely due to such factors as the increasing number of births to women 35 years and older, increasing rates of multiple births, increased management of maternal and fetal conditions (for example, inducing labor preterm if medical technology indicates it will increase the likelihood of survival), increased substance abuse (tobacco, alcohol), and increased stress (Goldenberg & Culhane, 2007). Ethnic

variations characterize preterm birth (Raglan & others, 2016; Sorbye, Wanigaratne, & Urgula, 2016). For example, in 2013, the likelihood of being born preterm was 11.4 percent for all U.S. infants and 10.4 percent for non-Latino White infants, but the rate was 16.8 percent for African American infants and 11.7 for Latino infants (Martin & others, 2015).

Incidence and Causes of Low Birth Weight Most, but not all, preterm babies are also low birth weight babies. The incidence of low birth weight varies considerably from country to country. In some countries, such as India and Sudan, where poverty is rampant and the health and nutrition of mothers are poor, the percentage of low birth weight babies reaches as high as 31 percent. In the United States, there has been an increase in low birth weight infants in the last two decades, and the U.S. low birth weight rate of 8.02 percent in 2013 was considerably higher than that of many other developed countries (Martin & others, 2015). For example, only 4 percent of the infants born in Sweden, Finland, Norway, and Korea are low birth weight, and only 5 percent of those born in New Zealand, Australia, and France are low birth weight.

Consequences of Low Birth Weight Many preterm and low birth weight infants are healthy, but as a group they have more health and developmental problems than do normal birth weight infants (Webb & others, 2014). The number and severity of these problems increase when infants are born very early and as their birth weight decreases (Griffin & others, 2015; Tchamo, Prista, & Leandro, 2016). Survival rates for infants who are born very early and very small have risen, but with this improved survival rate have come increased rates of severe brain damage (McNicholas & others, 2014). For preterm birth, the terms extremely preterm and very preterm are increasingly used (Kato & others, 2016; Ohlin & others, 2015). Extremely preterm infants are those born less than 28 weeks preterm, and very preterm infants are those born at less than 33 weeks of gestational age.

A “kilogram kid,” weighing less than 2.3 pounds at birth. What are some long-term outcomes of

weighing so little at birth?© Diether Endlicher/AP Images

Low birth weight children are more likely than their normal birth weight counterparts to develop a learning disability, attention deficit Page 69 hyperactivity disorder, autism

spectrum disorders, or breathing problems such as asthma (Leung & others, 2016; Schieve & others, 2016). Also, one study revealed that very preterm, low birth weight infants had abnormal axon development in their brain and impaired cognitive development at 9 years of age (Iwata & others, 2012). Approximately 50 percent of all low birth weight children are enrolled in special education programs.

Nurturing Low Birth Weight and Preterm Infants Two increasingly used interventions in the neonatal intensive care unit (NICU) are kangaroo care and massage therapy. Kangaroo care involves skin-to-skin contact in which the baby, wearing only a diaper, is held upright against the parent’s bare chest, much as a baby kangaroo is carried by its mother. Kangaroo care is typically practiced for two to three hours per day over an extended time in early infancy.

A new mother practices kangaroo care. What is kangaroo care? What are some outcomes of kangaroo

care?© iStockphoto.com/casenbina RF

Why use kangaroo care with preterm infants? Preterm infants often have difficulty coordinating their breathing and heart rate, and the close physical contact with the parent provided by kangaroo care can help stabilize the preterm infant’s heartbeat, temperature, and breathing (Boundy & others, 2016; Cho & others, 2016; Park & others, 2014). Preterm infants who experience kangaroo care also gain more weight than their counterparts who are not given this care (Faye & others, 2016). Also, a recent study discovered that preterm infants who experienced kangaroo care for 16 weeks had more complex electroencephalogram (EEG) patterns, which reflects neurological maturation) at 40 weeks of age than preterm infants who did not receive kangaroo care (Kaffashi & others, 2013).

And a recent study demonstrated the positive long-term benefits of kangaroo care (Feldman, Rosenthal, & Eidelman, 2014). In this study, maternal-newborn kangaroo care with preterm infants was linked to better respiratory and cardiovascular functioning, sleep patterns, and cognitive functioning from 6 months to 10 years of age. Further, a recent study in the United Kingdom found that the use of kangaroo care in neonatal units resulted in substantial cost savings mainly because of its reduction in diseases such as gastroenteritis and colitis (Lowson & others, 2016). And in another recent study, kangaroo care significantly reduced the amount of crying and improved heart rate stability in preterm infants (Choudhary & others, 2016).

A recent U.S. survey found that mothers had a much more positive view of kangaroo care than did neonatal intensive care nurses and that mothers were more likely to say that it should be provided daily (Hendricks-Munoz & others, 2013). There is concern that kangaroo care is not used more often in neonatal intensive care units (Kymre, 2014; Penn, 2015). Increasingly, kangaroo care is recommended as standard practice for all newborns (Seidman & others, 2015).

Many adults will attest to the therapeutic effects of receiving a massage. In fact, many will pay a premium to receive one at a spa on a regular basis. But can massage play a role in improving the developmental outcomes for preterm infants? A recent study found that both kangaroo care and massage therapy were equally effective in improving body weight and reducing length of hospital stay for low birth weight infants (Rangey & Sheth, 2015).

Many preterm infants experience less touch than full-term infants do because they are isolated in temperature-controlled incubators. Research by Tiffany Field and her colleagues (2001, 2007, 2010a; Diego, Field, & Hernandez-Reif, 2008, 2014; Field, Diego, & Hernandez-Reif, 2008, 2011) has led to a surge of interest in the role that massage might play in improving developmental outcomes for preterm infants. In Field’s first study Page 70 in this area, massage therapy consisting of firm stroking

with the palms of the hands was given three times per day for 15-minute periods to preterm infants (Field & others, 1986). The massage therapy led to 47 percent greater weight gain than did standard medical treatment. The massaged infants also were more active and alert than preterm infants who were not massaged, and they performed better on developmental tests.

Tiffany Field massages a

newborn infant. What types of infants has massage therapy been shown to help?© Dr. Tiffany Field

How Would You...?

As a health-care professional, how would you advise hospital administrators about implementing

kangaroo care or massage therapy in the newborn intensive care unit? In later studies, Field demonstrated the benefits of massage therapy for infants who faced a variety of problems. For example, preterm infants exposed to cocaine in utero who received massage therapy gained weight and improved their scores on developmental tests (Field, 2001). In other research, massage therapy improved the scores of HIV-exposed infants on both physical and mental scales, while also improving their hearing and speech (Perez & others, 2015). Also, one study investigated 1- to 3- month-old infants born to depressed adolescent mothers (Field & others, 1996). The infants of depressed mothers who received massage therapy had lower stress—as well as improved emotionality, sociability, and soothability—compared with non-massaged

infants of depressed mothers. In a review of the use of massage therapy with preterm infants, Field and her colleagues (2004) concluded that the most consistent findings involve two positive results: (1) increased weight gain and (2) discharge from the hospital three to six days earlier. One study revealed that the mechanisms responsible for increased weight gain as a result of massage therapy were stimulation of the vagus nerve (one of 12 cranial nerves leading to the brain) and in turn the release of insulin (a food absorption hormone) (Field, Diego, & Hernandez-Reif, 2011). Another recent study found that both massage therapy (moderate-pressure stroking) and exercise (flexion and extension of the limbs) led to weight gain in preterm infants (Diego, Field, & Hernandez-Reif, 2014). In this study, massage was linked to increased vagal activity while exercise was associated with increased calorie consumption.

Bonding A special component of the parent-infant relationship is bonding, the formation of a connection, especially a physical bond between parents and the newborn in the period shortly after birth. In the mid-twentieth century, U.S. hospitals seemed almost determined to deter bonding. Anesthesia given to the mother during delivery would make the mother drowsy, interfering with her ability to respond to and stimulate the newborn. Mothers and newborns were often separated shortly after delivery, and preterm infants were isolated from their mothers even more than full-term infants were separated from their mothers. In recent decades these practices have changed, but to some extent they are still followed in many hospitals. Do these practices do any harm? Some physicians believe that during the “critical period” shortly after birth the parents and newborn need to form an emotional attachment as a foundation for optimal development in years to come (Kennell, 2006; Kennell & McGrath, 1999). Although some research supports this bonding hypothesis (Klaus & Kennell, 1976), a body of research challenges the significance of the first few days of life as a critical period (Bakeman & Brown, 1980; Rode & others, 1981). Indeed, the extreme form of the bonding hypothesis—the idea that the newborn must have close contact with the mother in the first few days of life to develop optimally—simply is not true. Nevertheless, the weakness of the bonding hypothesis should not be used as an excuse to keep motivated mothers from interacting with their newborns. Such contact brings pleasure to many mothers and may dispel maternal anxiety about the baby’s Page 71health and safety. In some cases—including preterm infants, adolescent mothers, and mothers from disadvantaged circumstances—early close contact is key to establishing a climate for improved interaction after the mother and infant leave the hospital. Many hospitals now offer a rooming-in arrangement in which the baby remains in the mother’s room most of the time during its hospital stay. However, if parents choose not to use this rooming-in arrangement, the weight of the research suggests that this decision will not harm the infant emotionally (Lamb, 1994).

The Postpartum Period The weeks after childbirth present challenges for many new parents and their offspring. This is the postpartum period, the period after childbirth or delivery that lasts for about six weeks or until the mother’s body has completed its adjustment and has returned to a

nearly prepregnant state. It is a time when the woman adjusts, both physically and psychologically, to the process of childbearing.

Physical Adjustments A woman’s body makes numerous physical adjustments in the first days and weeks after childbirth (Durham & Chapman, 2014). She may have a great deal of energy or feel exhausted and let down. Though these changes are normal, the fatigue can undermine the new mother’s sense of well-being and confidence in her ability to cope with a new baby and a new family life (Runquist, 2007). A concern is the loss of sleep that the primary caregiver experiences in the postpartum period (Bei, Coo, & Trinder, 2015; Thomas & Spieker, 2016). In the 2007 Sleep in America survey, a substantial percentage of women reported loss of sleep during pregnancy and in the postpartum period (National Sleep Foundation, 2007). The loss of sleep can contribute to stress, marital conflict, and impaired decision making (Meerlo, Sgoifo, & Suchecki, 2008). A recent study, though, linked postpartum depression to poor-quality sleep (such as disrupted, fragmented sleep) rather than to lesser amounts of sleep (Park, Meltzer-Brody, & Stickgold, 2013). After delivery, the mother’s body undergoes sudden and dramatic changes in hormone production. When the placenta is delivered, estrogen and progesterone levels drop steeply and remain low until the ovaries start producing hormones again. Involution is the process by which the uterus returns to its prepregnant size five or six weeks after birth. Immediately following birth, the uterus weighs 2 to 3 pounds. By the end of five or six weeks, the uterus weighs 2 to 3½ ounces. Nursing the baby helps contract the uterus at a more rapid rate.

Emotional and Psychological Adjustments Emotional fluctuations are common for mothers in the postpartum period (Haran & others, 2014). For some women, emotional fluctuations decrease within several weeks after the delivery, but other women experience more long-lasting emotional swings. As shown in Figure 11, about 70 percent of new mothers in the United States have what are called the postpartum blues. About two to three days after birth, they begin to feel depressed, anxious, and upset. These feelings may come and go for several months after the birth, often peaking about three to five days after birth. Even without treatment, these feelings usually go away after one or two weeks.

Figure 11 Postpartum Blues and Postpartum Depression Among U.S. Women. Some health professionals refer to the postpartum period as the “fourth trimester.” Though the

time span of the postpartum period does not necessarily cover three months, the term “fourth

trimester” suggests continuity and emphasizes the importance of the first several months after

birth for the mother.

However, some women develop postpartum depression, which involves a major depressive episode that typically occurs about four weeks after delivery (Brummelte & Galea, 2016). In other words, women with postpartum depression have such strong feelings of sadness, anxiety, or despair that Page 72 for at least a two-week period they

have trouble coping with their daily tasks. Without treatment, postpartum depression

may become worse and last for many months (Di Florio & others, 2014). And many women with postpartum depression don’t seek help. For example, one study found that 15 percent of the women reported postpartum depression symptoms but less than half sought help (McGarry & others, 2009). Estimates indicate that 10 to 14 percent of new mothers experience postpartum depression.

The postpartum period is a time of

considerable adjustment and adaptation for both the mother and the father. Fathers can provide an

important support system for mothers, especially in helping mothers care for young infants. What kinds

of tasks might the father of a newborn do to support the mother?© Howard Grey/Getty Images RF

A recent research review identified the following risk factors for developing postpartum depression: a history of depression, depression and anxiety during pregnancy, neuroticism, low self-esteem, postpartum blues, poor marital relationship, and a low level of social support (O’Hara & McCabe, 2013). Also, in this research review, a number of perinatal-related stressors such as perinatal complications, infant health and temperament, and type of delivery (cesarean section, for example) were found to be potential risk factors for postpartum depression. A subset of women likely develop postpartum depression in the context of hormonal changes associated with late pregnancy and childbirth (O’Hara & McCabe, 2013). Also, a recent study found that depression during pregnancy, a history of physical abuse, migrant status, and postpartum physical complications were major risk factors for postpartum depression (Gaillard & others, 2014).

Several antidepressant drugs are effective in treating postpartum depression and appear to be safe for breast feeding women (Molyneaux, Trevillion, & Howard, 2015). Psychotherapy, especially cognitive therapy, also is effective in treating postpartum depression for many women (Carta & others, 2015; Sockol, 2015). In addition, engaging in regular exercise may help to relieve postpartum depression (Ko & others, 2013).

How Would You...?

As a human development and family studies professional, how would you talk with mothers

and fathers about vulnerabilities in mental health and relationships in the postpartum period? A mother’s postpartum depression can affect the way she interacts with her infant (Giallo & others, 2015; Kerstis & others, 2016). A research review concluded that the interaction difficulties of depressed mothers and their infants occur across cultures and socioeconomic status groups, and encompass less sensitivity of the mothers and less responsiveness on the part of infants (Field, 2010b). Several caregiving activities also are compromised, including feeding, sleep routines, and safety practices.

Fathers also undergo considerable adjustment in the postpartum period, even when they work away from home all day (Gawlik & others, 2014; Nishimura & others, 2015; Paulson & others, 2016). Many fathers feel that the baby comes first and gets all of the mother’s attention; some feel that they have been replaced by the baby. The father’s support and caring can play a role in whether the mother develops postpartum depression. One study revealed that higher support by fathers was related to lower incidence of postpartum depression in women (Smith & Howard, 2008).

Summary

The Evolutionary Perspective • Darwin proposed that natural selection fuels evolution. In evolutionary theory, adaptive

behavior is behavior that promotes the organism’s survival in a natural habitat.

• Evolutionary psychology holds that adaptation, reproduction, and “survival of the fittest” are

important in shaping behavior. Evolutionary developmental psychology emphasizes that

humans need an extended Page 73“juvenile” period to develop a large brain and learn the

complexity of social communities.

Genetic Foundations of Development • Except in the sperm and egg, the nucleus of each human cell contains 46 chromosomes,

which are composed of DNA. Short segments of DNA constitute genes, the units of

hereditary information that direct cells to reproduce and manufacture proteins. Genes act

collaboratively, not independently.

• Genes are passed on to new cells when chromosomes are duplicated during the processes of

mitosis and meiosis.

• Genetic principles include those involving dominant-recessive genes, sex-linked genes, and

polygenic inheritance.

• Chromosome abnormalities can produce Down syndrome and other problems; gene-linked

disorders, such as PKU, involve defective genes.

The Interaction of Heredity and Environment: The Nature-Nurture Debate • Behavior geneticists use twin studies and adoption studies to determine the strength of

heredity’s influence on development.

• In Scarr’s heredity-environment correlation view, heredity directs the types of environments

that children experience. Scarr identified three types of genotype-environment interactions:

passive, evocative, and active (niche-picking).

• The epigenetic view emphasizes that development is the result of an ongoing, bidirectional

interchange between heredity and environment. Recently, interest has developed regarding

how gene interaction influences development.

• The interaction of heredity and environment is complex, but we can create a unique

developmental path by changing our environment.

Prenatal Development • Prenatal development can be divided into three periods: germinal, embryonic, and fetal. The

growth of the brain during prenatal development is remarkable.

• A number of prenatal tests, including ultrasound sonography, chorionic villus sampling,

amniocentesis, maternal blood screening, and fetal MRI, can reveal whether a fetus is

developing normally.

• Approximately 10 to 15 percent of U.S. couples have infertility problems. Assisted

reproduction techniques, such as in vitro fertilization, are increasingly being used by infertile

couples.

• Some prescription drugs and nonprescription drugs can harm the unborn child. In particular,

the psychoactive drugs caffeine, alcohol, nicotine, cocaine, marijuana, and heroin can

endanger developing offspring. Other potential sources of harmful effects on the fetus

include environmental hazards, maternal diseases, maternal diet and nutrition, age, emotional

states and stress, and paternal factors.

• Prenatal care usually involves medical care services with a defined schedule of visits and

often encompasses educational, social, and nutritional services as well. Inadequate prenatal

care may increase the risk of infant mortality and result in low birth weight.

Birth and the Postpartum Period • Childbirth occurs in three stages. Childbirth strategies involve the childbirth setting and

attendants. In many countries, a midwife attends a childbearing woman. In some countries, a

doula helps with the birth. Methods of delivery include medicated, natural and prepared,

and cesarean.

• Being born involves considerable stress for the baby, but the baby is well prepared and

adapted to handle the stress. Low birth weight, preterm, and small for date infants are at risk

for developmental problems, although most of these infants are normal and healthy.

Kangaroo care and massage therapy have been shown to produce benefits for preterm infants.

• Early bonding has not been found to be critical in the development of a competent infant, but

close contact during the first few days after birth may reduce the mother’s anxiety and lead to

better interaction later.

• The postpartum period lasts for about six weeks after childbirth or until the body has returned

to a nearly prepregnant state; postpartum depression is a serious condition that may become

worse if not treated.