Oh, Baby! Prenatal and Newborn Development

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CHAPTER 3 PRENATAL DEVELOPMENT

Giving Birth to Peace

Lotfeh Mohamed El Mari, 11 years, Lebanon

Expectant mothers hope that their nearly full-term fetuses will benefit from and eventually contribute to a world of peace. How is the one-celled organism transformed into a baby with the capacity to participate in family life? What factors support or undermine this earliest period of development? Chapter 3 provides answers to these questions.

Reprinted with permission from The International Child Art Foundation, Washington, DC

WHAT’S AHEAD IN CHAPTER 3

3.1 Motivations for Parenthood

Why Have Children? • How Large a Family? • Is There a Best Time During Adulthood to Have a Child?

3.2 Prenatal Development

Conception • Germinal Period • Period of the Embryo • Period of the Fetus

3.3 Prenatal Environmental Influences

Teratogens • Other Maternal Factors

■ Biology and Environment: Self-Regulation Therapy for Children with Fetal Alcohol Spectrum Disorder (FASD)

■ Social Issues: Health: The Nurse–Family Partnership: Reducing Maternal Stress and Enhancing Child Development Through Social Support

3.4 The Importance of Prenatal Health Care

■ Cultural Influences: Culturally Sensitive Prenatal Health Care: Perspectives of Expectant Mothers

One fall, Yolanda and Jay enrolled in an evening section of my child development course, when Yolanda was just two months pregnant. In their early thirties, married for several years, and their careers well under way, they had decided to have a baby. Each week, they arrived for class full of questions: “How does the baby grow before birth?” “When is each organ formed?” “Has its heart begun to beat?” “Can it hear, feel, or sense our presence?”

Most of all, Yolanda and Jay wanted to do everything possible to make sure their baby would be born healthy. Yolanda started to wonder about her diet and whether she should keep up her daily aerobic workouts. And she asked whether an aspirin for a headache, a glass of wine at dinner, or a few cups of coffee during the workday might be harmful.

In this chapter, we answer Yolanda and Jay’s questions, along with a great many more that researchers have asked about the events before birth. We begin our discussion with these puzzling questions: Why is it that generation after generation, most couples want to become parents? And what factors influence their decision to have just one child or more than one?

Then we trace prenatal development, addressing both supports for healthy growth and damaging influences that threaten the child’s health and survival. Because the changes taking place during these nine months are so astounding, the prenatal environment can exert a powerful, lasting impact—for better or for worse—on physical and mental health. ■

3.1 MOTIVATIONS FOR PARENTHOOD

3.1 Discuss factors that contribute to contemporary adults’ decision making about parenthood, including timing of childbearing and family size.

What, in your view, are the benefits and drawbacks of having children? How large would your ideal family be, and why? Until just a few decades ago, the issue of whether to have children was, for many adults, a biological given or a compelling social expectation. Today, in Western industrialized nations, it is a matter of true individual choice. Effective contraception enables sexually active adults to avoid having children in most instances. And changing cultural values allow people to remain childless with far less fear of social criticism than a generation or two ago.

Nevertheless, the 6 percent of American 18- to 40-year-olds who currently say they do not want children is just slightly higher than the 5 percent who said so three decades ago. The desire for children remains the norm: In a survey of a large, nationally representative sample of U.S. adults of childbearing age, 90 percent said they already have children or are planning to have them (Gallup, 2013). Actually becoming parents, however, is affected by a complex array of contextual factors, including financial circumstances, religious values, partnership changes, career goals, health conditions, and availability of supportive government and workplace family policies (Mills et al., 2011; Vespa, 2017).

3.1.1 Why Have Children?

In addition to the contextual factors just mentioned, vital personal attributes called childbearing motivations—positive or negative inclinations toward the idea of parenthood—affect people’s decision to have children as well as their psychological adjustment to pregnancy and a baby’s arrival. In Western nations, these motivations have changed over time, increasingly emphasizing individual fulfillment and deemphasizing obligation to society (Frejka et al., 2008; Guedes et al., 2015).

Advantages and Disadvantages of Parenthood Mentioned by American and European Adults of Childbearing Age (in General Order of Importance)

When Americans and Europeans are asked about their childbearing motivations, they mention a variety of advantages and disadvantages, listed in Table 3.1. Although some ethnic and regional differences exist, in all groups highly rated reasons for having children include personal fulfillment—for example, the warm, affectionate relationship and opportunities for care and teaching that children provide. Also frequently mentioned are the deepening of a couple’s relationship that comes from sharing in a challenging but important life task, and the sense of future continuity that results from perpetuating a family line and passing on one’s heritage and values (Guedes, et al., 2015). Less important but still mentioned are social and economic returns, including being recognized as a family and having children to rely on as sources of caregiving and financial support late in life.

Table 3.1 Advantages anddbearing Age (in General Order of Importance)

ADVANTAGES

DISADVANTAGES

Giving and receiving warmth and affection and providing care and teaching

Enhancing life’s meaning

Nurturing a new person and personality

Creating one’s own family

Strengthening the couple relationship through a shared project

Fulfilling a partner’s desire for parenthood

Carrying on one’s family name, lineage, heritage, or values

Being accepted as a responsible and mature member of the community

Having a source of caregiving and economic support in later life

Risk of birth complications

Constant worries over and responsibility for children’s health, safety, and well-being

Fear that children will turn out badly, through no fault of one’s own

Role overload—not enough time to meet both child-rearing and job responsibilities

Risks of bringing up children in a world plagued by crime, war, and pollution

Financial strain and sacrifices

Reduced time to spend with partner

Loss of privacy

Sources: Guedes, et al., 2015; Miller, 2009.

Most adults also realize that having children means years of extra burdens and responsibilities. Among disadvantages of parenthood, they often cite risk of birth complications; constant worries over children’s health, safety, and well-being; fear that children will turn out badly; concerns about role overload (not enough time for both family and work responsibilities); and worries about bringing up children in a troubled world. The financial strains and sacrifices of child rearing also rank high. According to a conservative estimate, middle-income parents in the United States today will spend nearly $300,000 to rear a child from birth to age 18, and many will incur substantial additional expense for higher education (U.S. Department of Agriculture, 2017).

Look and Listen

Interview several parents of infants or preschoolers about the benefits and challenges of parenthood. Ask which issues they considered before starting a family. How deliberate about family planning were they?

Greater freedom to choose whether, when, and how to have children (see the discussion of reproductive choices in Chapter 2) makes contemporary family planning more challenging, as well as intentional, than in past generations. Still, about 30 percent of U.S. births are the result of unintended pregnancies, with most born to low-income, less educated mothers—circumstances associated with delayed prenatal care, premature birth, and child health problems (Bearak et al., 2018). Yet opportunities to explore childbearing motivations in high school, college, and community-based health education classes and through family-planning counseling might encourage more adults to make informed and personally meaningful decisions—a trend that would increase the chances that they would have children when ready, find parenting an enriching experience, and rear physically and mentally healthy children.

Among often-cited reasons for having children are the affectionate relationship and opportunity for care and teaching that a child provides.

Axel Bernstorff/Cultura Creative RF/Alamy Stock Photo

3.1.2 How Large a Family?

Prior to the economic recession of 2007–2009, the overall fertility rate, or lifetime births per woman, in developed countries was about 2.1. Since then, the U.S. fertility rate has declined by 16 percent, to 1.8. Fertility rates are similar, or even lower, in other industrialized nations: 1.9 in Sweden, 1.8 in Australia and the United Kingdom, 1.6 in Canada, 1.5 in Germany, 1.4 in Italy and Japan, and 1.3 in Spain (World Bank, 2018b).

A major reason for this drop in births is that increasing numbers of adults of childbearing age are delaying marriage and parenthood until their education is complete, their work lives are under way, and they are more secure economically (Vespa, 2017). As Figure 3.1 shows, the U.S. birthrate decline is substantial for women in their twenties, with small gains in births limited to women ages 35 and older (Centers for Disease Control and Prevention, 2018f; Pew Research Center, 2018e). Starting a family later is associated with having fewer children.

Average family size has declined in recent decades in most industrialized nations. But, contrary to popular belief, having more children does not reduce the intelligence or life chances of later-born children.

A smaller family size is compatible with the decision of increasing numbers of women to divide their energies between family and career. In addition, popular advice to prospective parents often includes limiting family size in the interests of “child-rearing quality,” based on the presumed ability of parents of fewer children to devote more affection, stimulation, and material resources to each child, thus enhancing the intellectual development of all. Do smaller families really make brighter children, as is commonly believed?

For years, researchers thought that earlier birth order and wider spacing might grant children more parental involvement and, therefore, result in more favorable cognitive outcomes. But two decades of research consistently indicates that the relationship of birth order and spacing to children’s intelligence is negligible (Damian & Roberts, 2015; Kanazawa, 2012; Rodgers et al., 2000; Wichman, Rodgers, & MacCallum, 2007). Rather, parents’ differential treatment of siblings is far more responsive to children’s personalities, interests, and behaviors than to these aspects of family structure.

Figure 3.1 Births to U.S. women by age in 2007 and 2017. Births declined for women in their twenties through mid-thirties while increasing for women 35 and older, reflecting the trend toward delayed parenthood. (Based on Centers for Disease Control and Prevention, 2018f.)

Furthermore, the well-documented association between large family size and lower intelligence test scores of all siblings can be entirely explained by a strong trend for low-SES mothers to give birth to more children. Most of these families suffer from poverty, which threatens all domains of development (see pages 70–71 in Chapter 2). Among children of well-educated, economically advantaged mothers, the family size–intelligence relationship disappears (Guo & VanWey, 1999; Wichman, Rodgers, & MacCallum, 2007). In sum, although many good reasons exist for limiting family size, the concern that additional births will reduce parenting quality and thus impair children’s skills and life chances is not warranted.

3.1.3 Is There a Best Time During Adulthood to Have a Child?

Yolanda, at age 32, is pregnant for the first time. Many people believe that women should, ideally, have children before 35 because the risk of having a baby with a chromosomal disorder rises sharply from then on. Advanced paternal age is associated with elevated risk of certain genetically influenced disorders as well (see page 60 in Chapter 2).

Reproductive capacity also declines with age. Between ages 25 and 34, 12 percent of women are affected, a figure that escalates to 39 percent for 35- to 39-year-olds and to 47 percent for 40- to 44-year-olds. Similarly, age affects male reproductive capacity. Amount of semen, concentration of sperm in each ejaculation, and quality of sperm decline gradually after age 35 (Chandra, Copen, & Stephen, 2013).

Highly educated women with demanding careers are especially likely to delay parenthood (Pew Research Center, 2015a). Many believe, incorrectly, that if they have difficulty conceiving, they can rely on reproductive technologies. But recall from Chapter 2 that the success of these procedures declines steadily with age. Although no one time during adulthood is best to begin parenthood, individuals who decide to put off pregnancy until their late thirties or early forties risk having fewer biological children than they desire or none at all.

3.2 PRENATAL DEVELOPMENT

3.2 List the three periods of prenatal development, and describe the major milestones of each.

The sperm and ovum that unite to form the new individual are uniquely suited for the task of reproduction. The ovum is a tiny sphere, measuring 1⁄175 inch in diameter—barely visible to the naked eye as a dot the size of the period at the end of this sentence. But in its microscopic world, it is a giant—the largest cell in the human body, making it a perfect target for the much smaller sperm, which measure only 1⁄500 inch.

3.2.1 Conception

About once every 28 days, in the middle of a woman’s menstrual cycle, an ovum bursts from one of her ovaries, two walnut-sized organs located deep inside her abdomen, and is drawn into one of two fallopian tubes—long, thin structures that lead to the hollow, softly lined uterus (see Figure 3.2). While the ovum is traveling, the spot on the ovary from which it was released, now called the corpus luteum, secretes hormones that prepare the lining of the uterus to receive a fertilized ovum. If pregnancy does not occur, the corpus luteum shrinks, and the lining of the uterus is discarded two weeks later with menstruation.

Conception. In this photo, taken with the aid of a powerful microscope, sperm penetrate the surface of the ovum, the largest cell in the human body. When one sperm succeeds in fertilizing the ovum, the resulting zygote begins to duplicate.

The male produces sperm in vast numbers—an average of 300 million a day—in the testes, two glands located in the scrotum, sacs that lie just behind the penis. In the final process of maturation, each sperm develops a tail that permits it to swim long distances, upstream in the female reproductive tract, through the cervix (opening of the uterus) and into the fallopian tube, where fertilization usually takes place. The journey is difficult, and many sperm die. Only 300 to 500 reach their destination. Once in the fallopian tube, sperm live for up to six days and can lie in wait for the ovum, which survives for only one day after its release from the ovary. However, most conceptions result from intercourse occurring during a three-day period—on the day of ovulation or during the two days preceding it (Mu & Fehring, 2014).

Figure 3.2 Female reproductive organs, showing fertilization, early cell duplication, and implantation. (From Before We Are Born, 9th ed., by K. L. Moore, T. V. N. Persaud, & M G. Torchia, p. 33. Copyright © 2016, adapted with permission from Elsevier, Inc.)

With conception, the story of prenatal development begins to unfold. The vast changes that take place during the 38 weeks of pregnancy are usually divided into three periods: (1) the germinal period, (2) the period of the embryo, and (3) the period of the fetus. As we consider each, you may find it useful to refer to Table 3.2 on page 92, which summarizes milestones of prenatal development.

3.2.2 Germinal Period

The germinal period lasts about two weeks, from fertilization and formation of the zygote until the tiny mass of cells drifts down and out of the fallopian tube and attaches itself to the wall of the uterus. The zygote’s first cell duplication is long and drawn out, taking about 30 hours. Gradually, new cells are added at a faster rate, forming a hollow, fluid-filled ball called a blastocyst that by the fourth day consists of 60 to 70 cells (refer again to Figure 3.2). The cells on the inside of the blastocyst, called the embryonic disk, will become the new organism; the outer ring of cells, termed the trophoblast, will become the structures that provide protective covering and nourishment.

Implantation

Between the seventh and ninth days, implantation occurs: The blastocyst burrows deep into the uterine lining. Surrounded by the woman’s nourishing blood, it starts to grow in earnest. At first, the trophoblast (protective outer layer) multiplies fastest. It forms a membrane, called the amnion, that encloses the developing organism in amniotic fluid, which helps keep the temperature of the prenatal world constant and provides a cushion against any jolts caused by the woman’s movement. A yolk sac emerges that produces blood cells until the developing liver, spleen, and bone marrow are mature enough to take over this function (Moore, Persaud, & Torchia, 2016).

Table 3.2 Milestones of Prenatal Development

Trimester

Prenatal Period

Weeks

Length and Weight

Major Events

First

Germinal

The one-celled zygote multiplies and forms a blastocyst.

The blastocyst burrows into the uterine lining. Structures that feed and protect the developing organism begin to form—amnion, chorion, yolk sac, placenta, and umbilical cord.

Embryo

3–4

5–8

¼ inch (6 mm)

1 inch (2.5 cm); 1/7ounce (4 g)

A primitive brain and spinal cord appear. Heart, muscles, ribs, backbone, and digestive tract begin to develop.

Many external body structures (face, arms, legs, toes, fingers) and internal organs form, and production and migration of neurons in the brain begin. The sense of touch starts to develop, and the embryo can move.

Fetus

9–12

3 inches (7.6 cm); less than 1 ounce (28 g)

Rapid increase in size begins. Nervous system, organs, and muscles become organized and connected, touch sensitivity extends to most of the body, and new behavioral capacities (kicking, thumb sucking, mouth opening, and rehearsal of breathing) appear. External genitals are well-formed, and the fetus’s sex is evident.

Second

13–24

12 inches (30 cm); 1.8 pounds (820 g)

The fetus continues to enlarge rapidly. In the middle of this period, the mother can feel fetal movements. Vernix and lanugo keep the fetus’s skin from chapping in the amniotic fluid. Most of the brain’s neurons are in place by 24 weeks. Eyes are sensitive to light, and the fetus reacts to sound.

Third

25–38

20 inches (50 cm); 7.5 pounds (3,400 g)

The fetus has a good chance of survival if born during this time. Size increases. Lungs mature. Rapid brain development, in neural connectivity and organization, enables sensory and behavioral capacities to expand. In the middle of this period, a layer of fat is added under the skin. Antibodies are transmitted from mother to fetus to protect against disease. Most fetuses rotate into an upside-down position in preparation for birth.

Sources: Moore, Persaud, & Torchia, 2016.

Photos (from top to bottom): © Claude Cortier/Science Source; © Dr. G. Moscoso/Science Source; © Claude Edelmann/Science Source; © James Stevenson/Science Source; © LENNART NILSSON, TT / SCIENCE PHOTO

The events of these first two weeks are delicate and uncertain. As many as 30 percent of zygotes do not survive this period. In some, the sperm and ovum do not join properly. In others, cell duplication never begins. By preventing implantation in these cases, nature eliminates most prenatal abnormalities (Sadler, 2014).

The Placenta and Umbilical Cord

By the end of the second week, cells of the trophoblast form another protective membrane—the chorion, which surrounds the amnion. From the chorion, tiny fingerlike villi, or blood vessels, emerge.1 As these villi burrow into the uterine wall, the placenta starts to develop. By bringing the embryo’s and mother’s blood close together, the placenta permits food and oxygen to reach the developing organism and waste products to be carried away. A membrane forms that allows these substances to be exchanged but prevents the mother’s and embryo’s blood from mixing directly (see Figure 3.3).

1 Recall from Table 2.2 on page 62 that chorionic villus sampling is the prenatal diagnostic method that can be performed earliest, at nine weeks after conception.

The placenta is connected to the developing organism by the umbilical cord, which first appears as a primitive body stalk and, during the course of pregnancy, grows to a length of 1 to 3 feet. The umbilical cord contains one large vein that delivers blood loaded with nutrients and two arteries that remove waste products. The force of blood flowing through the cord keeps it firm, so it seldom tangles while the embryo, like a space-walking astronaut, floats freely in its fluid-filled chamber (Moore, Persaud, & Torchia, 2016). By the end of the germinal period, the developing organism has found food and shelter.

Germinal period: seventh to ninth day. The fertilized ovum duplicates at an increasingly rapid rate, forming a hollow ball of cells, or blastocyst, by the fourth day after conception. Between the seventh and ninth day the blastocyst, as shown here magnified thousands of times, burrows into the uterine lining.

3.2.3 Period of the Embryo

The period of the embryo lasts from implantation through the eighth week of pregnancy. During these brief six weeks, the most rapid prenatal changes take place as the groundwork is laid for all body structures and internal organs. Because all parts of the body are forming, the embryo is especially vulnerable to interference with healthy development. But the short time span of embryonic growth helps limit opportunities for serious harm.

Last Half of the First Month

In the first week of this period, the embryonic disk forms three layers of cells: (1) the ectoderm, which will become the nervous system and skin; (2) the mesoderm, which will develop into the muscles, skeleton, circulatory system, and other internal organs; and (3) the endoderm, which will become the digestive system, lungs, urinary tract, and glands. These three layers give rise to all parts of the body.

Figure 3.3 Cross-section of the uterus, showing detail of the placenta. The embryo’s blood flows from the umbilical cord arteries into the chorionic villi and returns via the umbilical cord vein. The mother’s blood circulates in spaces surrounding the chorionic villi. A membrane between the two blood supplies permits food and oxygen to be delivered and waste products to be carried away. The two blood supplies do not mix directly. The umbilical arteries carry oxygen-poor blood (shown in blue) to the placenta, and the umbilical vein carries oxygen-rich blood (shown in red) to the fetus. (Adapted from Before We Are Born, 9th ed., by K. L. Moore, T. V. N. Persaud, & M. G. Torchia, p. 76. Copyright © 2016, reprinted with permission from Elsevier, Inc.)

At first, the nervous system develops fastest. The ectoderm folds over to form the neural tube, or primitive spinal cord. At 3½ weeks, the top swells to form the brain. While the nervous system is developing, the heart begins to pump blood, and muscles, backbone, ribs, and digestive tract appear. At the end of the first month, the curled embryo—only ¼ inch long—consists of millions of organized groups of cells with specific functions.

The Second Month

In the second month, growth continues rapidly. The eyes, ears, nose, jaw, and neck form. Tiny buds become arms, legs, fingers, and toes. Internal organs are more distinct: The intestines grow, the heart develops separate chambers, and the liver and spleen take over production of blood cells so that the yolk sac is no longer needed. Changing body proportions cause the embryo’s posture to become more upright.

Period of the embryo: fourth week. This 4-week-old embryo is only ¼-inch long, but many body structures have begun to form.

During the fifth week, production of neurons (nerve cells that store and transmit information) begins deep inside the neural tube at the astounding pace of more than 250,000 per minute (Jabès & Nelson, 2014). Once formed, neurons begin traveling along tiny threads to their permanent locations, where they will form the major parts of the brain.

By 8 weeks, the testes in the male start to develop and begin secreting the hormone testosterone, which will stimulate differentiation of male internal reproductive organs and the penis and scrotum during the coming month. In the absence of testosterone, female reproductive organs form.

By the end of this period, the embryo—about 1 inch long and 1/7 ounce in weight—can already sense its world. It responds to touch, particularly in the mouth area and on the soles of the feet. And it can move, although its tiny flutters are still too light to be felt by the mother (Moore, Persaud, & Torchia, 2016).

3.2.4 Period of the Fetus

The period of the fetus, from the ninth week to the end of pregnancy, is the longest prenatal period. During this “growth and finishing” phase, the organism increases rapidly in size.

The Third Month

In the third month, the organs, muscles, and nervous system start to become organized and connected. Touch sensitivity extends to most of the body (Hepper, 2015). When the brain signals, the fetus kicks, bends its arms, forms a fist, curls its toes, turns its head, opens its mouth, and even sucks its thumb, stretches, and yawns. The tiny lungs begin to expand and contract in an early rehearsal of breathing movements.

By the twelfth week, the external genitals are well-formed, and the sex of the fetus can be detected with ultrasound (Sadler, 2014). Other finishing touches appear, such as fingernails, toenails, tooth buds, and eyelids. The heartbeat can now be heard through a stethoscope.

Period of the embryo: seventh week. The embryo’s posture is more upright. Body structures—eyes, nose, arms, legs, and internal organs—are more distinct. The embryo now responds to touch and can also move. At less than one inch long and an ounce in weight, it is still too tiny to be felt by the mother.

Prenatal development is sometimes divided into trimesters, or three equal time periods. At the end of the third month, the first trimester is complete.

The Second Trimester

By the middle of the second trimester, between 17 and 20 weeks, the new being has grown large enough that the mother can feel its movements. Already, the fetus is remarkably active—in motion nearly 30 percent of the time—which helps strengthen the joints and muscles (DiPietro, Costigan, & Voegtline, 2015). A white, cheeselike substance called vernix emerges on the skin, protecting it from chapping during the long months spent bathing in the amniotic fluid. White, downy hair called lanugo also appears over the entire body, helping the vernix stick to the skin.

At the end of the second trimester, many organs are well-developed. And most of the brain’s billions of neurons are in place; few will be produced after this time. However, glial cells, which support and feed the neurons, continue to increase rapidly throughout the remaining months of pregnancy, as well as after birth. Consequently, brain weight increases tenfold from the twentieth week until birth (Roelfsema et al., 2004). At the same time, neurons begin forming synapses, or connections, at a rapid pace.

Period of the fetus: eleventh week. The brain and muscles of the rapidly growing fetus are better connected. The fetus can kick, bend its arms, open and close its hands and mouth, and suck its thumb. The yolk sac shrinks as the internal organs assume blood cell production.

Brain growth means new sensory and behavioral capacities. The 20-week-old fetus can be stimulated as well as irritated by sounds. And if a doctor looks inside the uterus using fetoscopy (see Table 2.2 on page 62), fetuses try to shield their eyes from the light with their hands, indicating that sight has begun to emerge (Moore, Persaud, & Torchia, 2016). Still, a fetus born at this time cannot survive. Its lungs are immature, and the brain cannot yet control breathing movements or body temperature.

The Third Trimester

During the final trimester, a fetus born early has a chance for survival. The point at which the baby can first survive, called the age of viability, occurs sometime between 22 and 26 weeks (Moore, Persaud, & Torchia, 2016). A baby born between the seventh and eighth months, however, usually needs oxygen assistance to breathe. Although the brain’s respiratory center is now mature, tiny air sacs in the lungs are not yet ready to inflate and exchange carbon dioxide for oxygen.

The brain continues to make great strides. The cerebral cortex, the seat of human intelligence, enlarges. Convolutions and grooves in its surface appear, permitting a dramatic increase in surface area that allows for maximum prenatal brain growth without the full-term baby’s head becoming too large to pass through the birth canal. Brain-imaging evidence reveals rapid gains in fetal neural organization: At first, neural connectivity increases within brain areas supporting specific functions, such as vision, movement, language, and integration of information. In the last six weeks, connections begin to form between these areas, yielding primitive brain networks (Thomason et al., 2014). This pattern of brain growth, which supports coordinated processing of information, will continue after birth.

Period of the fetus: twenty-second week. This fetus is almost 1 foot long and weighs slightly more than 1 pound. Its movements can be felt readily by the mother and by others who touch her abdomen. If born now, the fetus would have a slim chance of surviving.

As neural organization improves, the fetus spends more time awake. At 20 weeks, fetal heart rate reveals no periods of alertness. But by 28 weeks, fetuses are awake about 11 percent of the time, a figure that rises to 16 percent just before birth (DiPietro et al., 1996). Between 30 and 34 weeks, fetuses show rhythmic alternations between sleep and wakefulness that gradually increase in organization (Rivkees, 2003). Around 36 weeks, synchrony between fetal heart rate and motor activity peaks: A rise in heart rate is usually followed within five seconds by a burst of motor activity (DiPietro et al., 2006; DiPietro, Costigan, & Voegtline, 2015). These are clear signs that functioning brain networks have started to take shape in the brain.

By the end of pregnancy, the fetus takes on the beginnings of a personality. Fetal activity is linked to infant temperament. In one study, more active fetuses during the third trimester became 1-year-olds who could better handle frustration and 2-year-olds who were more active as well as less fearful, in that they more readily interacted with toys and with an unfamiliar adult in a laboratory (DiPietro et al., 2002). Perhaps fetal activity is an indicator of healthy neurological development, which fosters adaptability in childhood. The relationships just described, however, are modest. As we will see in Chapter 6, sensitive caregiving can modify the temperaments of children who have difficulty adapting to new experiences.

The third trimester brings greater responsiveness to external stimulation. As we will see when we discuss newborn capacities in Chapter 4, fetuses acquire taste and odor preferences from bathing in and swallowing amniotic fluid (its makeup is influenced by the mother’s diet). Between 23 and 30 weeks, the fetus is clearly sensitive to pain, so painkillers should be used in any surgical procedures (Lee et al., 2005). Around 29 weeks, fetuses can hear. When presented with a repeated auditory stimulus against the mother’s abdomen, they initially react with a rise in heart rate, brain-wave activity, and body movements (Kisilevsky, 2016). Then responsiveness gradually declines, indicating habituation (adaptation) to the sound. If a new auditory stimulus is introduced, heart rate and brain waves recover to a high level, revealing that the fetus recognizes the new sound as distinct from the original stimulus (Hepper, Dornan, & Lynch, 2012; Muenssinger et al., 2013). This indicates that fetuses can remember for at least a brief period.

Within the next six weeks, fetuses distinguish the tone and rhythm of different voices and sounds—learning that will serve as a springboard for language development. In various studies, they showed systematic heart-rate and brain-wave changes in response to the mother’s voice versus the father’s or a stranger’s, to their native language (English) versus a foreign language (Mandarin Chinese), and to a simple familiar melody (descending tones) versus an unfamiliar melody (ascending tones) (Granier-Deferre et al., 2003; Kisilevsky & Hains, 2011; Kisilevsky et al., 2009; Lecanuet et al., 1993; Lee & Kisilevsky, 2013; Voegtline et al., 2013). In one clever investigation, mothers read aloud Dr. Seuss’s lively book The Cat in the Hat each day during the last six weeks of pregnancy. After birth, their infants learned to turn on recordings of the mother’s voice by sucking on nipples (DeCasper & Spence, 1986). They sucked hardest to hear The Cat in the Hat—the sound they had come to know while still in the womb.

On the basis of these findings, would you recommend that expectant mothers provide fetuses with stimulation aimed at enhancing later development? Although specific forms of fetal stimulation, such as reading aloud, contribute to development in the short-term, they are unlikely to have a long-lasting impact because of the child’s constantly changing capacities and experiences, which can override the impact of fetal stimulation (Lecanuet, Granier-Deferre, & DeCasper, 2005). In addition, although ordinary stimulation contributes to sensory functioning, excessive input can be hazardous. For example, nonhuman animal studies indicate that a sensitive period (see page 23 in Chapter 1) exists in which the fetal ear is highly susceptible to injury (Pierson, 1996). During that time, prolonged exposure to sounds that are harmless to the mature ear can permanently damage fetal inner-ear structures.

Period of the fetus: thirty-sixth week. This fetus fills the uterus. To nourish it, the umbilical cord and placenta have grown large. Vernix, a cheeselike substance, protects the skin from chapping. The fetus has accumulated fat to aid temperature regulation after birth. In two more weeks, it will be full term.

In the final three months, the fetus gains more than 5 pounds and grows 7 inches. During the eighth month, lanugo typically is shed. A layer of fat is added to assist with temperature regulation. The fetus also receives antibodies from the mother’s blood that protect against illnesses, since the newborn’s immune system will not work well until several months after birth. In the last weeks, most fetuses assume an upside-down position, partly because of the shape of the uterus and partly because the head is heavier than the feet. Growth slows, and birth is about to take place.

3.3 PRENATAL ENVIRONMENTAL INFLUENCES

3.3a Cite factors that influence the impact of teratogens, and discuss evidence on the impact of known or suspected teratogens.

3.3b Describe the impact of additional maternal factors on prenatal development.

Although the prenatal environment is far more constant than the world outside the womb, many factors can affect the embryo and fetus. Yolanda and Jay learned that parents—and society as a whole—can do a great deal to create a safe environment for development before birth.

3.3.1 Teratogens

The term teratogen (from the Greek word teras, meaning “malformation”) refers to any environmental agent that causes damage during the prenatal period. The harm done by teratogens is not always simple and straightforward. It depends on the following factors:

Dose. As we discuss particular teratogens, you will see that larger doses over longer time periods usually have more negative effects.

Heredity. The genetic makeup of the mother and the developing organism plays an important role. Some individuals are better able than others to withstand harmful environments.

Other negative influences. The presence of several negative factors at once, such as additional teratogens, poor nutrition, and lack of medical care, can worsen the impact of a harmful agent.

Age. The effects of teratogens vary with the age of the organism at time of exposure. To understand this last idea, think back, once again, to the sensitive period concept introduced in Chapter 1. A sensitive period is a limited time span in which a part of the body or a behavior is biologically prepared to develop rapidly. During that time, it is especially sensitive to its surroundings. If the environment is harmful, then damage occurs, and recovery is difficult and sometimes impossible.

Figure 3.4 on page 98 summarizes prenatal sensitive periods. Look at it carefully, and you will see that some parts of the body, such as the brain and eye, have long sensitive periods that extend throughout prenatal development. For other parts, including the limbs and palate, sensitive periods are much shorter. Figure 3.4 also indicates that we can make some general statements about the timing of harmful influences. In the germinal period, before implantation, teratogens rarely have any impact. If they do, the tiny mass of cells is usually so damaged that it dies. Serious defects are most likely to arise during the embryonic period, when the foundations of all body parts emerge. During the fetal period, teratogenic damage is usually minor. However, organs such as the brain, ears, eyes, teeth, and genitals can still be strongly affected.

The effects of teratogens go beyond immediate physical damage. Some health effects may show up years later. Growing evidence indicates that certain teratogens exert long-term effects epigenetically, by modifying gene expression (see page 82 in Chapter 2) (Markunas et al., 2014). Furthermore, delayed psychological consequences can occur indirectly, as a result of physical damage. For example, a defect resulting from drugs the mother took during pregnancy can affect others’ reactions to the child as well as the child’s ability to explore the environment. Over time, parent–child interaction, peer relations, and cognitive, emotional, and social development may suffer.

Figure 3.4 Sensitive periods in prenatal development. Each organ or structure has a sensitive period, during which its development may be disturbed. Blue horizontal bars indicate highly sensitive periods. Green horizontal bars indicate periods that are somewhat less sensitive to teratogens, although damage can occur. (From Before We Are Born, 9th ed., by K. L. Moore, T. V. N. Persaud, & M. G. Torchia, p. 313. Copyright © 2016, adapted with permission from Elsevier, Inc.)

Notice how an important idea about development discussed in earlier chapters is at work here: bidirectional influences between child and environment. Now let’s look at what researchers have discovered about a variety of teratogens.

Prescription and Nonprescription

Drugs In the early 1960s, the world learned a tragic lesson about drugs and prenatal development. At that time, a sedative called thalidomide was widely available in Canada, Europe, and South America. When taken by mothers 4 to 6 weeks after conception, thalidomide produced gross deformities of the embryo’s developing arms and legs and, less frequently, damage to the ears, heart, kidneys, and genitals. About 7,000 infants worldwide were affected. Recent evidence suggests that thalidomide may exert its damaging effects through epigenetic mechanisms, including gene methylation (Ross & Desai, 2017). Furthermore, as children exposed to thalidomide grew older, many scored below average in intelligence. Perhaps the drug damaged the central nervous system directly. Or the child-rearing conditions of these youngsters with severe physical deformities may have impaired their intellectual development.

Another medication, a synthetic hormone called diethylstilbestrol (DES), was widely prescribed between 1945 and 1970 to prevent miscarriages. As daughters of these mothers reached adolescence and young adulthood, they showed unusually high rates of cancer of the vagina, malformations of the uterus, and infertility. When they tried to have children, their pregnancies more often resulted in prematurity, low birth weight, and miscarriage than those of non-DES-exposed women. Young men showed an increased risk of genital abnormalities and cancer of the testes (Goodman, Schorge, & Greene, 2011; Reed & Fenton, 2013).

Currently, the most widely used, potent teratogenic medication is a vitamin A derivative called isotretinoin, prescribed to treat severe acne and taken by hundreds of thousands of women of childbearing age in industrialized nations. Exposure during the first trimester results in eye, ear, skull, brain, heart, and immune system abnormalities (Yook et al., 2012). U.S. regulations for prescribing isotretinoin require female users to commit to avoiding pregnancy by using two methods of birth control.

Any drug with a molecule small enough to penetrate the placental barrier can enter the embryonic or fetal bloodstream. Yet many pregnant women continue to take over-the-counter medications without consulting their doctors. Some research suggests that aspirin use is linked to brain damage leading to impaired motor control, inattention, and overactivity, though other evidence fails to confirm these findings (Barr et al., 1990; Kozer et al., 2003; Thompson et al., 2014; Tyler et al., 2012). Coffee, tea, cola, and cocoa contain another frequently consumed drug, caffeine. High doses increase the risk of low birth weight (Sengpiel et al., 2013). Persistent intake of antidepressant medication is associated with an elevated incidence of premature delivery, low birth weight, respiratory distress at birth, and delayed motor development in infancy, but contrary evidence exists (Grigoriadis et al., 2013; Huang et al., 2014; Robinson, 2015).

A pregnant woman consults a nurse about her medications and their potential effects on embryonic and fetal development. Before taking any drug—prescription or nonprescription—expectant mothers must seriously consider its risks.

Because children’s lives are involved, we must take findings like these seriously. At the same time, we cannot be sure that these drugs actually cause the problems just mentioned. Often mothers take more than one drug. If the embryo or fetus is injured, it is hard to tell which drug might be responsible or whether other factors correlated with drug taking are at fault. Until we have more information, the safest course of action is the one Yolanda took: Avoid drugs as far as possible.

Unfortunately, many women do not know that they are pregnant during the early weeks of the embryonic period, when exposure to medications (and other teratogens) can be of greatest threat. In some instances, such as antidepressant use by severely depressed mothers, the benefits of drug treatment may outweigh its risks.

Illegal Drugs

The use of highly addictive mood-altering drugs, such as cocaine and heroin, has become more widespread, especially in poverty-stricken areas where these drugs provide a temporary escape from a daily life of hopelessness. Nearly 6 percent of U.S. pregnant women take these substances (Substance Abuse and Mental Health Services Administration, 2016).

Babies born to users of cocaine, heroin, or methadone (a less addictive drug used to wean people away from heroin) are at risk for a wide variety of problems, including prematurity, low birth weight, brain abnormalities, physical defects, breathing difficulties, and death around the time of birth (Behnke & Smith, 2013). In addition, these infants are born drug-addicted. They are often feverish and irritable and have trouble sleeping, and their cries are abnormally shrill—a common symptom among stressed newborns (Anand & Campbell-Yeo, 2015; Barthell & Mrozek, 2013). When mothers with many problems of their own must care for these babies, who are difficult to calm down, cuddle, and feed, behavior problems are likely to persist.

Throughout the first year, heroin- and methadone-exposed infants are less attentive to the environment than nonexposed babies, and their motor development is slow. After infancy, some children get better, while others remain jittery and inattentive (Hans & Jeremy, 2001). The kind of parenting they receive may explain why problems persist for some but not for others.

Evidence on cocaine suggests that some prenatally exposed babies develop lasting difficulties. Cocaine constricts the blood vessels, causing oxygen delivered to the developing organism to fall for 15 minutes following a high dose. It also can lead to deficits in production of neurons and their synaptic connections, as well as alter the chemical balance in the fetus’s brain. These effects may contribute to an array of cocaine-associated physical malformations, especially of the central nervous system and heart; brain hemorrhages and seizures; and delayed physical growth (Cain, Bornick, & Whiteman, 2013; Grewen et al., 2014; Li et al., 2013). An array of studies report perceptual, motor, attention, memory, language, reasoning, and externalizing behavior problems that persist into adolescence (Coyle, 2013; Richardson et al., 2015; Singer et al., 2015).

Other investigations, however, reveal no major negative effects of prenatal cocaine exposure (Ackerman, Riggins, & Black, 2010; Allen et al., 2014; Buckingham-Howes et al., 2013). These contradictory findings illustrate how difficult it is to isolate the precise damage caused by illegal drugs. Cocaine users vary greatly in the amount, potency, and purity of the cocaine they ingest. Also, they often take several drugs, display other high-risk behaviors, suffer from poverty and other stressors, and engage in insensitive caregiving—factors that worsen outcomes for children (Molnar et al., 2014). Researchers have yet to determine exactly what accounts for findings of cocaine-related damage in some studies but not in others.

Another drug, marijuana, has been legalized for medical and recreational use in some U.S. states. Studies have linked prenatal marijuana exposure to increased risk of low birth weight and newborn death and to attention, memory, and academic achievement difficulties; impulsivity and overactivity; and depression as well as anger and aggression in childhood and adolescence (Behnke & Smith, 2013; Goldschmidt et al., 2004; Gray et al., 2005; Hayatabakhsh et al., 2012; Jutras-Aswad et al., 2009). But as with heroin and cocaine, these consequences are not well-established.

However, a growing number of researchers believe that prenatal marijuana exposure delivers an initial, silent “hit” to the fetal brain, inducing epigenetic changes that heighten sensitivity to postnatal environmental stressors. Inadequate parenting, nutritional deprivation, or other stressful conditions may then deliver a second, powerful “hit” that impairs central nervous system functioning profoundly, resulting in long-lasting cognitive and emotional deficits (Calvigioni et al., 2014; Maccarrone et al., 2014; Richardson, Hestor, & McLemore, 2016). Both animal and human longitudinal studies offer support for this hypothesis, though more evidence is needed to confirm it.

Overall, the effects of illegal drugs are less consistent than the impact of two legal substances to which we now turn: tobacco and alcohol.

Tobacco

Although smoking has declined in Western nations, about 7 percent of U.S. women smoke during their pregnancies (Centers for Disease Control and Prevention, 2018b). The best-known effect of smoking during the prenatal period is low birth weight. But the likelihood of other serious consequences, such as miscarriage, prematurity, cleft lip and palate, blood vessel abnormalities, impaired heart rate and breathing during sleep, infant death, and asthma and cancer later in childhood, also increases (Geerts et al., 2012; Havstad et al., 2012; Howell, Coles, & Kable, 2008; Mossey et al., 2009). The more cigarettes a mother smokes, the greater the chances that her baby will be affected. If a pregnant woman stops smoking at any time, even during the third trimester, she reduces the likelihood that her infant will be born underweight and suffer from future problems (Polakowski, Akinbami, & Mendola, 2009). The earlier she stops, the more beneficial the effects.

Even when a baby of a smoking mother appears to be born in good physical condition, slight behavioral abnormalities may threaten the child’s development. Newborns of smoking mothers are less attentive to sights and sounds, display more muscle tension, are more emotionally reactive to frustration, and more often have colic (persistent crying). These findings suggest subtle negative effects on brain development (Espy et al., 2011; Shisler et al., 2017 Wiebe et al., 2014). Consistent with this view, prenatally exposed children and adolescents tend to have shorter attention spans, difficulties with impulsivity and overactivity, poorer memories, lower intelligence and achievement test scores, and higher levels of disruptive, aggressive behavior (Espy et al., 2011; Thakur et al., 2013).

Exactly how can smoking harm the fetus? Nicotine, the addictive substance in tobacco, constricts blood vessels, lessens blood flow to the uterus, and causes the placenta to grow abnormally. This reduces the transfer of nutrients, so the fetus gains weight poorly. Also, nicotine raises the concentration of carbon monoxide in the bloodstreams of both mother and fetus. Carbon monoxide displaces oxygen from red blood cells, damaging the central nervous system and slowing fetal body growth (Behnke & Smith, 2013). Other toxic chemicals in tobacco, such as cyanide and cadmium, contribute to its damaging effects. Research also suggests that prenatal exposure to cigarette smoke is a powerful epigenetic modifier of DNA, inducing widespread gene methylation that persists into adulthood (Lee et al., 2015; Tehranifar et al., 2018). These epigenetic changes may contribute to sustained impulsivity, overactivity, and oppositional behavior in childhood, adolescence, and beyond.

Maternal smoking during the prenatal period is associated with many serious consequences, including low birth weight and prematurity. This infant, born many weeks before his due date, breathes with the aid of a respirator.

From one-third to one-half of nonsmoking pregnant women are “passive smokers” because their partners, relatives, or co-workers use cigarettes. Passive smoking is also related to low birth weight, infant death, childhood respiratory illnesses, and possible long-term attention, learning, and behavior problems (Best, 2009; Hawsawi, Bryant, & Goodfellow, 2015). Clearly, expectant mothers should avoid smoke-filled environments.

Alcohol

In his moving book The Broken Cord, Michael Dorris (1989), a Dartmouth College anthropology professor, described what it was like to rear his adopted son Adam, a Sioux Indian, who was born with fetal alcohol spectrum disorder (FASD), a term that encompasses a range of physical, mental, and behavioral outcomes caused by prenatal alcohol exposure. Children with FASD are generally given one of the following four diagnoses, which vary in severity: fetal alcohol syndrome (FAS), partial fetal alcohol syndrome (p-FAS), alcohol-related neurodevelopmental disorder (ARND), and alcohol-related birth defects (ARBD) (see Table 3.3) (Hoyme et al., 2016).

Table 3.3 Diagnostic Criteria for Fetal Alcohol Spectrum Disorder (FASD)

Diagnosis

Criteria

Fetal alcohol syndrome (FAS)

• At least two of three characteristic facial abnormalities

– Short eyelid openings (measured horizontally)

– Thin upper lip

– Smooth or flattened philtrum (indentation between the nose and upper lip)

• Deficient physical growth (height or weight at or below the tenth percentile for child’s age)

• Deficient brain growth or profound brain injury, indicated either by a small head (at or below the tenth percentile) or confirmed through brain imaging

• Substantial cognitive impairment and behavioral impairment in self -regulation

Partial fetal alcohol syndrome (p-FAS)

• At least two of the three characteristic facial abnormalities

• Either deficient physical growth or profound brain injury

• Either substantial cognitive impairment or behavioral impairment in self-regulation

Alcohol-related neurodevelopmental disorder (ARND)

• Deficient brain growth or profound brain injury

• Either substantial cognitive impairment or behavioral impairment in self-regulation

• Typical physical growth and absence of facial abnormalities

Alcohol-related birth defects (ARBD)

• At least two of the three characteristic facial abnormalities

• Other alcohol-related physical malformations—for example, of the eyes, ears, heart, urinary tract, or hands

• Typical physical growth, absence of brain abnormalities, and absence of cognitive and behavioral deficits

Source: Hoyme et al., 2016.

Adam was diagnosed as having FAS. As is typical of this disorder, his mother drank heavily during pregnancy. Frequent binge drinking (consuming four or more drinks on a single occasion), especially early in pregnancy, elevates risk for FAS and p-FAS (Popova et al., 2018). For ARND, and ARBD, prenatal alcohol exposure, though confirmed, is usually less pervasive than for FAS and p-FAS (Mattson, Crocker, & Nguyen, 2012).

The brain abnormalities associated with FASD show up in diverse symptoms—for example, poor memory, language and communication, impulse control, attention span, activity level (overactivity), planning and reasoning, motor coordination, and academic and social skills. Additional physical defects—of the eyes, ears, nose, throat, heart, genitals, skeleton, hands, urinary tract, or immune system—may also be present.

Even when provided with enriched diets, babies with FAS or p-FAS fail to catch up in physical size during infancy or childhood. Cognitive and behavioral impairments are also permanent: In his teens and twenties, Adam had trouble concentrating and keeping a routine job, and he suffered from poor judgment. For example, he would buy something and not wait for change or would wander off in the middle of a task. He died at age 23, after being hit by a car. Adolescents and young adults with FAS, p-FAS, or ARND generally display persisting attention, impulse-control, and motor-coordination deficits, school failure, inappropriate social and sexual behaviors, trouble with the law, and mental health problems, including inability to manage stress, depression, and alcohol and drug abuse (Bertrand & Dang, 2012; Hellemans et al., 2010; Roszel, 2015). Still, as the Biology and Environment box on the following page illustrates, some recovery is possible for children with p-FAS and ARND through carefully designed intervention.

This child, whose mother drank heavily during pregnancy, has all three of the facial abnormalities characteristic of fetal alcohol syndrome (FAS): short eyelid openings, which make her eyes look widely spaced; a thin upper lip; and a flattened philtrum (the indentation between her nose and upper lip).

How does alcohol produce its devastating effects? First, it interferes with production and migration of neurons in the primitive neural tube. Neuroimaging findings confirm damage to many brain structures and abnormalities in brain functioning, including electrical and chemical activity involved in transferring messages from one part of the brain to another (de la Monte & Kril, 2014; Memo et al., 2013). Second, the body uses large quantities of oxygen to metabolize alcohol. A pregnant woman’s heavy drinking draws away oxygen that the developing organism needs for cell growth. Third, both animal and human research reveals widespread epigenetic changes in response to alcohol consumption, including altered methylation of many genes, that contribute to physical and brain abnormalities (Laufer et al., 2017; Lussier et al., 2018; Mandal et al., 2017). Other evidence suggests that paternal alcohol use around the time of conception can also alter gene expression, thereby playing a role in these damaging outcomes (Basavarajappa & Subbanna, 2016).

About 10 percent of U.S. pregnant women report drinking during the previous month, one-third of whom admit to binge drinking. An estimated 3 percent of U.S. infants are affected, with diagnoses of p-FAS, ARND, and ARBD occurring 3 to 4 times more often than full-blown FAS (Centers for Disease Control and Prevention, 2015; Roozen et al., 2016). Globally, an estimated 630,000 infants with FASD are born each year. The incidence is especially high in Eastern Europe, and South Africa has the highest rate in the world, at 11 percent (Lange et al., 2017).

As with heroin and cocaine, alcohol abuse is higher in poverty-stricken women. It is especially high among Native Americans, for whom the risk of a baby born with FAS is 20 to 25 times greater than for the rest of the U.S. population (Rentner, Dixon, & Lengel, 2012). Unfortunately, when affected girls later become pregnant, the poor judgment caused by the syndrome often prevents them from understanding why they themselves should avoid alcohol. Thus, the tragic cycle is likely to be repeated in the next generation.

How much alcohol is safe during pregnancy? Even mild drinking, less than one drink per day, can lead to slow physical growth, brain damage, and cognitive and behavioral impairments (Flak et al., 2014; Martinez-Frias et al., 2004). Recall that other factors—both genetic and environmental—can make some fetuses more vulnerable to teratogens. Therefore, no amount of alcohol is safe. Couples planning a pregnancy and expectant mothers should avoid alcohol entirely.

Biology and EnvironmentSelf-Regulation Therapy for Children with Fetal Alcohol Spectrum Disorder (FASD)

Self-regulation difficulties are so pervasive among children with the brain abnormalities caused by prenatal alcohol exposure that they are now regarded as a core deficit of FASD. A weakened capacity to manage one’s thoughts, emotions, and actions is apparent in high emotional reactivity, distractibility, and overactivity as early as infancy and in poor planning, reasoning, and social awareness in childhood. These behaviors are strong predictors of the high levels of mental health problems and lawbreaking associated with FASD by adolescence.

Until recently, treatments for FASD have shown either minimal or inconsistent effects (Murawski et al., 2015). But a new approach that targets a central deficit of diagnosed children—impaired self-regulation skills—shows considerable promise.

In several experiments, researchers randomly assigned 8- to 12-year-olds with p-FAS or ARND to either a therapy or a no-treatment control condition. In each investigation, therapy was based on a widely applied self-regulation intervention for school-age children called the Alert Program (Williams & Shellenberger, 1996). In 12 weekly sessions, Alert shows children how to monitor their thoughts, feelings, and behavior, noticing when their arousal level interferes with their ability to engage in everyday learning and social activities.

Using the analogy of a car engine running at different speeds, the Alert therapist helps children recognize when their engines are running “too quickly” (wired) or “too slowly” (sluggish). Then the therapist teaches strategies for adjusting the engine to run “just right” (focused on the task at hand). These include steps for planning ahead, identifying emotions in themselves and others, expressing feelings appropriately, and solving social problems, such as how to cooperate in a game with a peer. Finally, the therapist provides children with practice in selecting strategies independently and applying those strategies appropriately outside the therapeutic situation.

Relative to controls, children experiencing Alert improved considerably in regulation of behavior, especially in ability to inhibit irrelevant actions and control their emotions (Nash et al., 2015). In addition, parents of Alert children rated them as better regulated and as having fewer behavior problems—an outcome still evident at a six-month follow-up.

Furthermore, magnetic resonance imaging (MRI) brain scans gathered before and after the intervention revealed that Alert led to denser gray matter (darker tissue consisting mainly of neurons and their connective fibers) in regions of the cerebral cortex crucial for self-regulation, indicating that new synapses had formed (Soh et al., 2015). Treatment children also displayed more efficient functioning in these cerebral regions, which correlated with their ability to inhibit impulsive responding while playing a computer game (Nash et al., 2018). These findings suggest that it is possible to modify some of the brain damage caused by fetal alcohol exposure.

The researchers noted that the gains of treatment children were greatest on simple rather than complex self-regulation tasks—findings not surprising, given the significant brain pathology associated with p-FAS and ARND. At the same time, the shift in parents’ views of their children following Alert is impressive: It may spark favorable changes in the parent–child relationship that lead to continued progress, especially as therapists equip parents with knowledge of Alert therapeutic techniques.

The mother of a child with FASD helps her daughter with a homework assignment. School-age children with p-FAS and ARND who experienced Alert self-regulation therapy improved in ability to inhibit irrelevant actions and control their emotions, and their parents viewed them as having fewer behavior problems.

Radiation

In Chapter 2, we saw that ionizing radiation can cause mutation, damaging DNA in ova and sperm. When mothers are exposed to radiation during pregnancy, the embryo or fetus can suffer additional harm. Defects due to ionizing radiation were tragically apparent in children born to pregnant women who survived the bombing of Hiroshima and Nagasaki during World War II. Similar abnormalities surfaced in the nine months following the 1986 Chernobyl, Ukraine, nuclear power plant accident. After each disaster, the incidence of miscarriage and babies born with brain damage, physical deformities, and slow physical growth rose dramatically. The risk of brain injury and intellectual disability is greatest from the end of the first trimester through the second trimester, when production and migration of neurons is especially high (Verreet et al., 2016; Yang, Ren, & Tang, 2017). Evacuation of residents in areas near the Japanese nuclear facility damaged by the March 2011 earthquake and tsunami was intended to prevent these devastating outcomes.

Even when a radiation-exposed baby seems unaffected, problems may appear later. For example, even low-level radiation, resulting from industrial leakage or medical radiation procedures, can increase the risk of childhood cancer (Fushiki, 2013). In middle childhood, prenatally exposed Chernobyl children had abnormal brain-wave activity, lower intelligence test scores, and rates of language and emotional disorders two to three times greater than those of nonexposed children in the surrounding area. Furthermore, the more tension parents reported, due to forced evacuation from their homes and worries about living in irradiated areas, the poorer their children’s emotional functioning (Loganovskaja & Loganovsky, 1999; Loganovsky et al., 2008). Stressful rearing conditions seemed to combine with the damaging effects of prenatal radiation to impair children’s development.

Women should do their best to avoid medical radiation during pregnancy. If dental, thyroid, chest, or other X-rays are necessary, insisting on the use of an abdominal shield is a key protective measure.

A pregnant woman is tested for exposure to radiation at an evacuation center following the Fukushima, Japan, nuclear power plant disaster in 2011. Radiation can cause devastating harm to the embryo or fetus and is particularly dangerous for the developing brain from the end of the first trimester through the second trimester.

Environmental Pollution

In industrialized nations, an astounding number of potentially dangerous chemicals are released into the environment, and many new pollutants are introduced each year. When 10 newborns were randomly selected from U.S. hospitals for analysis of umbilical cord blood, researchers uncovered a startling array of industrial contaminants—287 in all (Houlihan et al., 2005). They concluded that many babies are “born polluted” by chemicals that not only impair prenatal development but increase the chances of life-threatening diseases and health problems later on.

Certain pollutants cause severe prenatal damage. In the 1950s, an industrial plant released waste containing high levels of mercury into a bay providing seafood and water for the town of Minamata, Japan. Many children born at the time displayed physical deformities, intellectual disability, abnormal speech, difficulty in chewing and swallowing, and uncoordinated movements. High levels of prenatal mercury exposure disrupt production and migration of neurons, causing widespread brain damage (Caserta et al., 2013; Hubbs-Tait et al., 2005). Prenatal mercury exposure from maternal seafood diets predicts deficits in speed of cognitive processing, attention, and memory during the school years (Boucher et al., 2010, 2012; Lam et al., 2013). Pregnant women are wise to avoid eating long-lived predatory fish, such as swordfish, albacore tuna, and shark, which are heavily contaminated with mercury.

For many years, polychlorinated biphenyls (PCBs) were used to insulate electrical equipment, until research showed that, like mercury, they entered waterways and the food supply. In Taiwan, prenatal exposure to high levels of PCBs in rice oil resulted in low birth weight, discolored skin, deformities of the gums and nails, brain-wave abnormalities, and delayed cognitive development (Chen & Hsu, 1994; Chen et al., 1994). Steady, low-level PCB exposure is also harmful. Women who frequently ate PCB-contaminated fish, compared with those who ate little or no fish, had infants with lower birth weights, smaller heads, persisting attention and memory difficulties, and lower intelligence test scores in childhood (Boucher, Muckle, & Bastien, 2009; Polanska, Jurewicz, & Hanke, 2013; Stewart et al., 2008).

Another teratogen, lead, is present in paint flaking off the walls of old buildings and in certain materials used in industrial occupations. High levels of prenatal lead exposure are related to prematurity, low birth weight, brain damage, and a wide variety of physical defects. Even at low levels, affected infants and children show slightly poorer mental and motor development (Caserta et al., 2013; Jedrychowski et al., 2009).

Prenatal exposure to dioxins—toxic compounds resulting from incineration and burning of fuels, such as coal or oil—is linked to thyroid abnormalities in infancy and to an increased incidence of breast and uterine cancers in women, perhaps through altering hormone levels (ten Tusscher & Koppe, 2004). Even tiny amounts of dioxin in the paternal bloodstream cause a dramatic change in the sex ratio of offspring: Affected men father nearly twice as many girls as boys (Ishihara et al., 2007). Dioxin seems to impair the fertility of Y-bearing sperm prior to conception.

Finally, persistent air pollution inflicts substantial prenatal harm. Exposure to traffic-related fumes and smog is associated with reduced infant head size, low birth weight, elevated infant death rates, impaired lung and immune-system functioning, and later respiratory illnesses (Proietti et al, 2013; Ritz et al., 2014). In several large-scale studies, prenatal exposure to air pollution was linked to several childhood cancers, including leukemia and tumors of the eye and brain (Ghosh et al., 2013; Lavigne et al., 2017).

Infectious Disease

Most infectious illnesses women experience during pregnancy, such as the common cold, seem to have no impact on the embryo or fetus. However, as Table 3.4 illustrates, a few can cause extensive damage.

Viruses

In the mid-1960s, a worldwide epidemic of rubella (three-day, or German, measles) led to the birth of more than 20,000 U.S. babies with serious defects and to 13,000 fetal and newborn deaths. Consistent with the sensitive period concept, the greatest damage occurs when rubella strikes during the embryonic period. More than 50 percent of infants whose mothers become ill during that time are born with some or all of the following: deafness; eye deformities, including cataracts; heart, genital, urinary, intestinal, bone, and dental defects; and intellectual disability. Infection during the fetal period is less harmful, but low birth weight, hearing loss, and bone defects may still occur. The organ damage inflicted by prenatal rubella often leads to lifelong health problems, including severe mental illness, diabetes, cardiovascular disease, and thyroid and immune-system dysfunction in adulthood (Duszak, 2009; Waldorf & McAdams, 2013). Routine vaccination in infancy and childhood has made new rubella outbreaks unlikely in industrialized nations. But over 100,000 cases of prenatal infection continue to occur each year, primarily in developing countries in Africa and Asia with weak or absent immunization programs (World Health Organization, 2017b).

Table 3.4 Effects of Some Infectious Diseases During Pregnancy

Disease

Miscarriage

Physical Malformations

Intellectual Disability

Low Birth Weight and Prematurity

Viral

Acquired immune deficiency syndrome (AIDS)

✓

Chickenpox

✓

Cytomegalovirus

✓

Herpes simplex 2 (genital herpes)

✓

Mumps

✓

✗

Rubella (German measles)

✓

Zika

✓

Bacterial

Chlamydia

✓

✗

✓

Syphilis

✓

Tuberculosis

✓

Parasitic

Malaria

✓

✗

✓

Toxoplasmosis

✓

✓ = established finding, ✗ = no present evidence, ? = possible effect that is not clearly established

Sources: Beckham et al., 2016; Kliegman et al., 2015; Waldorf & McAdams, 2013.

The human immunodeficiency virus (HIV), which can lead to acquired immune deficiency syndrome (AIDS), a disease that destroys the immune system, has infected increasing numbers of women over the past three decades. In developing countries, where 95 percent of new infections occur, more than half affect women. In South Africa, for example, 30 percent of all pregnant women are HIV-positive (Burton, Giddy, & Stinson, 2015). Untreated HIV-infected expectant mothers pass the deadly virus to the developing organism 10 to 20 percent of the time.

AIDS progresses rapidly in infants. By 6 months, weight loss, diarrhea, and repeated respiratory illnesses are common. The virus also causes brain damage, as indicated by seizures, gradual loss in brain weight, and delayed cognitive and motor development. Most untreated prenatal AIDS babies die by age 3 (Siberry, 2015). Antiretroviral drug therapy reduces prenatal transmission to less than 1 to 2 percent, and several babies born with HIV for whom aggressive retroviral treatment began within 2 days after birth appeared free of the disease (McNeil, 2014). However, antiretroviral drugs remain unavailable to at least one-third of HIV-infected pregnant women in developing countries (World Health Organization, 2017a).

As Table 3.4 reveals, the developing organism is especially sensitive to the family of herpes viruses, for which no vaccine exists. Among these, cytomegalovirus (the most frequent prenatal infection, transmitted through respiratory or sexual contact) and herpes simplex 2 (transmitted sexually) are especially dangerous. In both, the virus invades the mother’s genital tract, infecting babies either during pregnancy or at birth. Both diseases often have no symptoms, very mild symptoms, or symptoms with which people are unfamiliar, thereby increasing the likelihood of contagion. Pregnant women who are not in a mutually monogamous relationship are at greatest risk.

A Brazilian child lovingly cradles his 1-year-old brother who was born with microcephaly, a condition characterized by a severely damaged brain and unusually small head. The baby’s mother contracted the Zika virus during pregnancy.

A 2015 outbreak in Brazil of the Zika virus (mainly transmitted by mosquito but also through sexual contact with an infected person) drew widespread attention because of an associated rise in the number of babies born with microcephaly (unusually severe brain injury, evident in extremely small head size, as low as the first percentile) and eye deformities (Beckham et al., 2016; Brasil et al., 2016). As the disease spread through Central America, South America, and the Caribbean, Zika was declared a public health emergency. Expectant mothers are advised not to travel to countries or regions with Zika outbreaks. At present, no vaccine is available.

Bacterial and Parasitic Diseases

Table 3.4 also includes several bacterial and parasitic diseases. Among the most common is toxoplasmosis, caused by a parasite found in many animals. Pregnant women may become infected from handling contaminated soil while gardening, having contact with the feces of infected cats, or eating raw or undercooked meat or unwashed fruits and vegetables. About 40 percent of women who have the disease transmit it to the developing organism. If it strikes during the first trimester, it is likely to cause eye and brain damage. Later infection is linked to mild visual and cognitive impairments (Wallon et al., 2013). Expectant mothers can avoid toxoplasmosis by having pet cats checked for the disease, and turning over the care of litter boxes and the garden to other family members, and making sure that the meat they eat is well-cooked.

3.3.2 Other Maternal Factors

Besides avoiding teratogens, expectant parents can support prenatal development in other ways. In the following sections, we examine the influence of maternal exercise, nutrition, emotional well-being, blood type, and age.

Exercise

In healthy, physically fit women, regular moderate exercise, such as walking, swimming, biking, or an aerobic workout, is related to improved fetal cardiovascular functioning, higher birth weight, and a reduction in risk of certain complications, such as pregnancy-induced maternal diabetes, high blood pressure, and premature birth (Artal, 2015; Jukic et al., 2012). However, frequent, vigorous exercise, especially late in pregnancy, results in lower birth weight than in healthy, nonexercising controls (Clapp et al., 2002; Leet & Flick, 2003). Hospital-sponsored childbirth education programs frequently offer exercise classes and suggest appropriate routines that help prepare for labor and delivery.

During the last trimester, when the abdomen grows very large, mothers have difficulty moving freely and often must cut back on exercise. Most women, however, do not engage in sufficient moderate exercise during pregnancy to promote their own and their baby’s health. An expectant mother who remains fit experiences fewer physical discomforts in the final weeks.

Pregnant women with health problems, such as circulatory difficulties or a history of miscarriages, should consult their doctor about a physical fitness routine. For these mothers, exercise (especially the wrong kind) can endanger the pregnancy.

Nutrition

During the prenatal period, when children are growing more rapidly than at any other time, they depend totally on the mother for nutrients. A healthy diet, consisting of a gradual increase in calories that results in a weight gain of 25 to 30 pounds (10 to 13.5 kilograms) helps ensure the health of mother and baby.

Prenatal malnutrition can cause serious damage to the central nervous system. The poorer the mother’s diet, the greater the loss in brain weight, especially if malnutrition occurs during the third trimester, when the brain is increasing rapidly in size. An inadequate diet during pregnancy can also distort the structure of the liver, kidney, pancreas, and other organs, predisposing the child to later health problems. As Figure 3.5 illustrates, large-scale studies reveal a consistent link between low birth weight and high blood pressure, cardiovascular disease, and diabetes in adulthood, even after many other prenatal and postnatal health risks were controlled (Johnson & Schoeni, 2011).

Because poor nutrition suppresses development of the immune system, prenatally malnourished babies frequently catch respiratory illnesses. In addition, they are often irritable and unresponsive to stimulation. Like drug-addicted newborns, they have a high-pitched cry that is particularly distressing to their caregivers. In poverty-stricken families, these effects quickly combine with a stressful home life. Delays in motor, attention, and memory development, low intelligence test scores, and serious learning problems become more apparent with age (Monk, Georgieff, & Osterholm, 2013).

Many studies show that providing pregnant women with an adequate quantity of food has a substantial impact on the health of their newborn babies. Vitamin–mineral enrichment is also crucial. For example, taking a folic acid supplement around the time of conception reduces by more than 70 percent abnormalities of the neural tube, such as anencephaly and spina bifida (see Table 2.2 on page 62). Folic acid supplementation early in pregnancy also lessens the risk of other physical defects, including cleft lip and palate, circulatory system and urinary tract abnormalities, and limb deformities. Furthermore, adequate folic acid intake during the last 10 weeks of pregnancy cuts in half premature delivery and low birth weight (Goh & Koren, 2008; Hovdenak & Haram, 2012).

Figure 3.5 Relationship of low birth weight to disease risk in adulthood. In a follow-up of more than 2,000 U.S. births at age 50, low birth weight was associated with a greatly increased incidence of high blood pressure, heart disease, stroke, and diabetes after many other prenatal and postnatal health risks were controlled. (Based on Johnson & Schoeni, 2011.)

Because of these findings, U.S. government guidelines recommend that all women of childbearing age consume 0.4 milligram of folic acid per day. For women who have previously had a pregnancy affected by a neural tube defect, the recommended amount is 4 milligrams (dosage must be carefully monitored, as excessive intake can be harmful) (Centers for Disease Control and Prevention, 2017d). Because many U.S. pregnancies are unplanned, government regulations mandate that bread, flour, rice, pasta, and other grain products be fortified with folic acid.

A government-supported farmers’ market nutrition program enables this low-income expectant mother to purchase fruits and vegetables. A maternal diet rich in vitamins and minerals can help protect prenatal brain development and prevent diverse birth defects.

Other vitamins and minerals also have established benefits. Enriching women’s diets with calcium helps prevent maternal high blood pressure and low birth weight. Adequate magnesium and zinc reduce the risk of many prenatal and birth complications (Hovdenak & Haram, 2012). Fortifying table salt with iodine virtually eradicates infantile hypothyroidism—a condition of stunted physical growth and brain injury caused by prenatal iodine deficiency that is a common cause of intellectual disability in many parts of the world (Williams, 2008). And sufficient vitamins C and E and iron beginning early in pregnancy promote placental growth, healthy birth weight, and brain development. Prenatal iron deficiency, in particular, is linked to deficiencies in neural connectivity and structural alterations in the brain. Affected children, adolescents, and young adults score lower on measures of self-regulation, memory, and motor skills (Kennedy et al., 2016; Klemmensen et al., 2009; Lukowski et al., 2010; Monk et al., 2016). Nevertheless, a supplement program should complement, not replace, efforts to improve maternal diets during pregnancy. For women who do not get enough food or an adequate variety of foods, multivitamin tablets are a necessary, but not sufficient, intervention.

Although prenatal malnutrition is highest in developing countries, it also occurs in the industrialized world. The U.S. Special Supplemental Food Program for Women, Infants, and Children (WIC), which provides food packages and nutrition education to low-income pregnant women, reaches about 90 percent of those who qualify because of their extremely low incomes (U.S. Department of Agriculture, 2018). But many U.S. women who need nutrition intervention are not eligible for WIC.

Emotional Stress

When women experience severe emotional stress during pregnancy, their babies are at risk for a wide variety of difficulties. Intense anxiety—especially during the first two trimesters—is associated with higher rates of miscarriage, prematurity, low birth weight, physical defects, infant respiratory and digestive illnesses, colic (persistent infant crying), sleep disturbances, and irritability during the child’s first three years (Dunkel-Shetter & Lobel, 2012; Glover, Ahmed-Salim, & Capron, 2016; Field, 2011). Prenatal stressors consistently found to impair later physical and psychological well-being include chronic strain due to poverty; partner abuse; major negative life events such as divorce or death of a family member; disasters such as earthquakes or terrorist attacks; and fears specific to pregnancy and childbirth, including persistent anxiety about the health and survival of the baby and oneself. It is important to note that mild to moderate occasional stress has no adverse impact.

How can severe maternal stress affect prenatal development? When we experience fear and anxiety, stress hormones released into our bloodstream—such as cortisol and epinephrine (adrenaline), known as the “flight or fight” hormones—cause us to be “poised for action.” Large amounts of blood are sent to parts of the body involved in the defensive response—the brain, the heart, and the muscles in the arms, legs, and trunk. Blood flow to other organs, including the uterus, may be reduced. As a result, the fetus is deprived of a full supply of oxygen and nutrients.

Maternal stress hormones also cross the placenta, causing a dramatic rise in fetal stress hormones (evident in the amniotic fluid) and, therefore, in fetal heart rate, blood pressure, blood glucose, and activity level (Kinsella & Monk, 2009; Weinstock, 2008). Excessive fetal stress is related to structural alterations in the infant brain that are linked to mood disorders in later life (O’Donnell & Meaney, 2016; Sandman, Glynn, & Davis, 2016). Infants and children of mothers who experienced severe prenatal anxiety display cortisol levels that are either abnormally high or abnormally low, both of which signal reduced physiological capacity to manage stress. Recall from Chapter 2 that prenatal epigenetic changes, through gene methylation, may be partly or largely responsible (Monk et al., 2016).

Maternal emotional stress during pregnancy is associated with diverse negative behavioral outcomes in childhood and adolescence, including anxiety, depression, short attention span, anger, aggression, overactivity, and lower intelligence test scores, above and beyond the impact of other risks, such as maternal smoking during pregnancy, low birth weight, postnatal maternal anxiety, and low SES (Coall et al., 2015; Monk, Georgieff, & Osterholm, 2013). Furthermore, similar to prenatal malnutrition, overwhelming the fetus with maternal stress hormones heightens susceptibility to later illness, including infectious diseases in childhood and cardiovascular disease and diabetes in adulthood (Nielsen et al., 2011; Reynolds, 2013).

However, stress-related prenatal complications are greatly reduced when mothers have partners, other family members, or friends who offer social support (Bloom et al., 2013; Luecken et al., 2013). The relationship of social support to positive pregnancy outcomes and subsequent child development is particularly strong for economically disadvantaged women, who often lead highly stressful lives (see the Social Issues: Health box on page 110).

Look and Listen

List prenatal environmental factors that can compromise later cognitive and social development. Ask several adults who hope someday to be parents to explain what they know about each factor. How great is their need for prenatal education?

RH Factor Incompatibility

When inherited blood types of mother and fetus differ, serious problems sometimes result. The most common cause of these difficulties is Rh factor incompatibility. When the mother is Rh-negative (lacks the Rh blood protein) and the father is Rh-positive (has the protein), the baby may inherit the father’s Rh-positive blood type. (Because Rh-positive blood is dominant and Rh-negative blood is recessive, the chances are good that a baby will be Rh-positive.) If even a little of a fetus’s Rh-positive blood crosses the placenta into the Rh-negative mother’s bloodstream, she begins to form antibodies to the foreign Rh protein. If these enter the fetus’s system, they destroy red blood cells, reducing the oxygen supply to organs and tissues. Intellectual disability, miscarriage, heart damage, and infant death can occur.

It takes time for the mother to produce Rh antibodies, so firstborn children are rarely affected. The risk increases with each additional pregnancy. Fortunately, Rh incompatibility can be prevented in most cases. After the birth of each Rh-positive baby, Rh-negative mothers are routinely given a vaccine to prevent the buildup of antibodies. In emergency cases, blood transfusions can be performed immediately after delivery or, if necessary, even before birth.

Maternal Age

First births to women in their thirties and early forties have increased dramatically over the past several decades (Martin et al., 2018b). Many people are delaying childbearing until their education is complete, their careers are established, and they know they can support a child. In Chapter 2, we noted that women who delay childbearing until their thirties or forties face increased risk of infertility, miscarriage, and babies with chromosomal defects. Are other pregnancy complications more common for older mothers? Research indicates that healthy women in their thirties have about the same rates as those in their twenties. Thereafter, as Figure 3.6 reveals, complication rates increase, with a sharp rise among 50- to 55-year-olds—an age at which, because of menopause (end of menstruation) and aging reproductive organs, few women can conceive naturally (Salihu et al., 2003; Usta & Nassar, 2008).

Figure 3.6 Relationship of maternal age to prenatal and birth complications. Complications increase after age 40, with a sharp rise between 50 and 55 years. See page 111 for a description of preeclampsia. (Adapted from Salihu et al., 2003.)

Social Issues: HealthThe Nurse–Family Partnership: Reducing Maternal Stress and Enhancing Child Development Through Social Support

At age 17, Denise—an unemployed high-school dropout living with her disapproving parents—gave birth to Tara. Having no one to turn to for help during pregnancy and beyond, Denise felt overwhelmed and anxious much of the time. Tara was premature and had breathing difficulties, cried uncontrollably, slept erratically, and suffered from frequent minor illnesses throughout her first year. When she reached school age, she had trouble keeping up academically, and her teachers described her as distractible, unable to sit still, angry, and uncooperative.

The Nurse–Family Partnership—currently implemented in hundreds of counties across 40 U.S. states, Washington, D.C., U.S. Virgin Islands, and many Tribal communities, and internationally in Australia, Canada, Bulgaria, Norway, England, Northern Ireland, and Scotland—is a voluntary home visiting program for first-time, economically disadvantaged expectant mothers like Denise. Its goals are to reduce pregnancy and birth complications, promote competent early caregiving, and improve family conditions, thereby protecting children from lasting adjustment difficulties.

A registered nurse visits the home weekly during the first month after enrollment, twice a month during the remainder of pregnancy and through the middle of the child’s second year, and then monthly until age 2. In these sessions, the nurse provides the mother with intensive social support—a sympathetic ear; assistance in accessing health and other community services and the help of family members (especially fathers and grandmothers); and encouragement to finish high school, find work, and engage in future family planning.

To evaluate the program’s effectiveness, researchers randomly assigned large samples of mothers at risk for high prenatal stress (due to teenage pregnancy, poverty, and other negative life conditions) to nurse-visiting or comparison conditions (just prenatal care, or prenatal care plus infant referral for developmental problems). Families were followed through their child’s school-age years and, in one experiment, into adolescence (Kitzman et al., 2010; Olds et al., 2004, 2007; Rubin et al., 2011).

As kindergartners, Nurse–Family Partnership children obtained higher language and intelligence test scores. And at both ages 6 and 9, the children of home-visited mothers in the poorest mental health during pregnancy exceeded comparison children in academic achievement and displayed fewer behavior problems. Furthermore, from their baby’s birth on, home-visited mothers were on a more favorable life course: They had fewer subsequent births, longer intervals between their first and second births, more frequent contact with the child’s father, more stable intimate partnerships, less welfare dependence, and a greater sense of control over their lives—key factors in reducing subsequent prenatal stress and in protecting children’s development. Perhaps for these reasons, adolescent children of home-visited mothers continued to be advantaged in academic achievement and reported less alcohol use and drug-taking than comparison-group agemates.

Other findings revealed that professional nurses, compared with trained paraprofessionals, were far more effective in preventing outcomes associated with prenatal stress, including high infant fearfulness to novel stimuli and delayed mental development (Olds et al., 2002). Nurses were probably more proficient in individualizing program guidelines to fit the strengths and challenges faced by each family. They also might have had unique legitimacy as experts in the eyes of stressed mothers, more easily convincing them to take steps to reduce pregnancy complications that can trigger persisting developmental problems—such as those Tara displayed.

The Nurse–Family Partnership is highly cost-effective (Miller, 2015). For every $1 spent, it saves more than five times as much in public spending on pregnancy complications, preterm births, and child and youth health, learning, and behavior problems.

The Nurse–Family Partnership provides this first-time mother with regular home visits from a registered nurse. In follow-up research, children of home-visited mothers developed more favorably—cognitively, emotionally, and socially—than comparison children.

In the case of teenage mothers, does physical immaturity cause prenatal complications? As we will see in Chapter 4, infants born to teenagers have a higher rate of problems, but not directly because of maternal age. Most pregnant teenagers come from low-income backgrounds, where stress, poor nutrition, and health problems are common.

3.4 THE IMPORTANCE OF PRENATAL HEALTH CARE

3.4 Explain why early and regular health care is vital during the prenatal period.

Yolanda’s pregnancy, like most others, was free of complications. But unexpected difficulties can arise, especially if mothers have health problems. For example, an estimated 9 percent of expectant women are diagnosed with gestational diabetes, impaired glucose tolerance that emerges during pregnancy (DeSisto, Kim, & Sharma, 2014). All diabetic women need careful prenatal monitoring. Extra glucose in the mother’s bloodstream causes the fetus to grow larger than average, making pregnancy and birth problems more common. Furthermore, these infants are at increased risk of becoming overweight or obese and developing type 2 diabetes (Kampmann et al., 2015). Maternal high blood glucose also greatly elevates the chances of physical malformations and compromises prenatal brain development: It is linked to poorer attention, memory, and learning in infancy and early childhood (Hami et al., 2015).

Another complication, experienced by 5 to 10 percent of pregnant women, is preeclampsia (sometimes called toxemia), in which blood pressure increases sharply and the face, hands, and feet swell in the last half of pregnancy. Untreated preeclampsia can cause brain hemorrhages and kidney failure in expectant mothers, damage to the placenta, and fetal death. Usually, hospitalization, bed rest, and drugs can lower blood pressure to a safe level (Bokslag et al., 2016). If not, the baby must be delivered at once.

Unfortunately, 6 percent of pregnant women in the United States wait until after the first trimester to seek prenatal care or receive none at all. As Figure 3.7 shows, inadequate health care is far more common among low-income, ethnic minority mothers. Their infants are three times more likely to be born underweight and five times more likely to die than babies of mothers who receive early medical attention (Child Trends, 2015). Although government-sponsored health services for low-income pregnant women have expanded, some do not qualify and must pay for at least part of their care. As we will see when we address cross-national comparisons of health care policies in Chapter 4, in nations where affordable health care is universally available, late-care pregnancies and maternal and infant health problems are greatly reduced.

Figure 3.7 Expectant mothers in the United States with late (after the first trimester) or no prenatal care. From 7 to 11 percent of low-income ethnic minority mothers, and about 10 percent of adolescent mothers, receive inadequate prenatal care. (Based on Child Trends, 2015.)

Cultural InfluencesCulturally Sensitive Prenatal Health Care: Perspectives of Expectant Mothers

Compared with their European-American counterparts, low-income, ethnic minority expectant mothers are consistently less likely to access early and regular prenatal care—a difference linked to increased rates of low birth weight, prematurity, newborn death, and other negative birth outcomes (Cox et al., 2011; Kitsantas & Gaffney, 2010). When minority mothers do come in for prenatal appointments, they tend to report more negative experiences with health care providers (Wheatley et al., 2008). They perceive the care they receive to be poor quality, which discourages them from further seeking care, with profound implications for maternal and newborn health.

In several studies, researchers asked ethnic minority mothers who had recently given birth about their prenatal health care experiences. Many highlighted inadequacies in provider–patient communication while expressing a strong desire for culturally sensitive care. Noting that too often, doctors and nurses focused narrowly on completing required tests and conveying results, one mother concluded, “[W]e’re numbers and not people” (Coley et al., 2018, p. 161).

Though they readily acknowledged the need for medical procedures, minority mothers regarded the interpersonal side of prenatal visits as essential to quality care. An African-American mother illustrated what culturally sensitive care meant to her: “[for example] being aware of if you have a sickle-cell patient, … really doing your homework on the emotional side of what it means” (p. 161).

Hispanic mothers described provider–patient communication as especially challenging, due to language barriers and the fears of many that seeking prenatal care might threaten their immigrant status. In addition, they perceived doctors and nurses who rushed through appointments while appearing impatient and unfriendly as rude, angry, uncaring, and unreliable. In contrast, they judged those who took time to help reticent or confused patients to be caring and believable (Bergman & Connaughton, 2013). Spanish-speaking mothers consistently stressed the importance of having Spanish-speaking doctors, nurses, or interpreters available to overcome cultural differences, ensure patient understanding, and avoid medical errors.

Many new mothers noted that lack of cultural competence increased the chances that health care providers would harbor biased assumptions and behave disrespectfully. In a survey of several thousand new mothers, 20 percent of minority respondents reported poor treatment by doctors, nurses, or front desk staff due to race, ethnicity, or language (Attanasio & Kozhimannil, 2015). Discrimination in health care settings is associated with an array of negative outcomes, including unraveling of patient trust, reduced patient adherence to treatment recommendations, missed subsequent appointments, and declines in patient health (Hausmann et al., 2011; Weech-Maldonado et al., 2012).

Increasing the cultural sensitivity of prenatal care by strengthening provider–patient communication is vital for improving health outcomes for babies. In one strategy called group prenatal care, after each medical checkup, trained leaders provide low-income ethnic minority expectant mothers with a group discussion session—conducted in their native language—and encourage them to talk about important health issues (Carter et al., 2016; Catling et al., 2015). Compared to mothers receiving traditional brief appointments with little opportunity to ask questions, participants in group prenatal care are more satisfied with their health care experiences and engage in more health-promoting behaviors, and the incidence of prematurity and low birth weight is reduced.

Participants in a group prenatal care program meet after individual checkups to discuss important health issues in a culturally sensitive environment. Compared to mothers receiving traditional brief appointments, group care mothers experience a reduced incidence of prematurity and low birth weight.

Centering Healthcare Institute

Besides financial hardship, situational barriers (difficulty finding a doctor, getting an appointment, and arranging transportation) and personal barriers (psychological stress, the demands of taking care of other young children, family crises, and ambivalence about the pregnancy) can prevent mothers from seeking prenatal care (Mazul, Salm Ward, & Ngui, 2017). Many also engage in high-risk behaviors, such as smoking and drug abuse, which they do not want to reveal to health professionals.

Applying What We Know

Do’s and Don’ts for a Healthy Pregnancy

Don’t

Do make sure that you have been vaccinated against infectious diseases that are dangerous to the embryo and fetus, such as rubella, before you get pregnant. Most vaccinations are not safe during pregnancy.

Do see a doctor as soon as you suspect that you are pregnant, and continue to get regular medical checkups throughout pregnancy.

Do eat a well-balanced diet and take vitamin–mineral supplements, as prescribed by your doctor, both prior to and during pregnancy. Gain 25 to 30 pounds gradually.

Do obtain literature from your doctor, library, or bookstore about prenatal development. Ask your doctor about anything that concerns you.

Do keep physically fit through moderate exercise. If possible, join a special exercise class for expectant mothers.

Do avoid emotional stress. If you are a single expectant mother, find a relative or friend on whom you can rely for emotional support.

Do get plenty of rest. An overtired mother is at risk for pregnancy complications.

Do enroll in a prenatal and childbirth education class with your partner or other companion. When parents know what to expect, the nine months before birth can be one of the most joyful times of life.

Don’t take any drugs without consulting your doctor.

Don’t smoke. If you have already smoked during part of your pregnancy, cut down or, better yet, quit. If other members of your family smoke, ask them to quit or to smoke outside.

Don’t drink alcohol from the time you decide to get pregnant.

Don’t engage in activities that might expose your embryo or fetus to environmental hazards, such as radiation or chemical pollutants. If you work in an occupation that involves these agents, ask for a safer assignment or a leave of absence.

Don’t engage in activities that might expose your embryo or fetus to harmful infectious diseases, such as toxoplasmosis.

Don’t choose pregnancy as a time to go on a diet.

Don’t gain too much weight during pregnancy. A very large weight gain is associated with complications.

For these women, assistance in making appointments, drop-in child-care centers, and free or low-cost transportation are vital. As the Cultural Influences box on page 112 reveals, culturally sensitive health-care practices, emphasizing open communication between health-care providers and pregnant women that is respectful of patients’ values and needs, are also helpful. Refer to Applying What We Know above, which lists “do’s and don’ts” for a healthy pregnancy, based on our discussion of the prenatal environment.

During a routine visit, a woman views an ultrasound image of her developing fetus. All pregnant women need regular prenatal care to protect their health and that of their babies.

Ask Yourself

Connect ■ Using what you learned about research strategies in Chapter 1, explain why it is difficult to determine the prenatal effects of many environmental agents, such as drugs and pollution.

Apply ■ Nora, pregnant for the first time, believes that a few cigarettes and a glass of wine a day won’t be harmful. Provide Nora with research-based reasons for not smoking or drinking.

Reflect ■ If you had to choose five environmental influences to publicize in a campaign aimed at promoting healthy prenatal development, which ones would you choose, and why?

Summary

3.1 Motivations for Parenthood (p. 87)

3.1 Discuss factors that contribute to contemporary adults’ decision making about parenthood, including timing of childbearing and family size.

Compared to a few decades ago, today adults in Western industrialized nations are freer to choose whether, when, and how to have children. Among contextual factors that affect their decision making are financial circumstances, religious values, partnership changes, career goals, and government and workplace family policies.

Childbearing motivations have also changed over time, increasingly emphasizing individual fulfillment and deemphasizing obligation to society.

In the United States and other industrialized nations, the overall fertility rate has declined substantially over the past decade, a trend largely due to delayed marriage and parenthood, which results in adults having fewer children.

Contrary to widespread belief, smaller families do not make brighter children. The higher birth rate of low-SES women accounts for the association between large family size and lower intelligence test scores of all siblings.

Reproductive capacity declines with age, especially after 35, and risk of chromosomal and other genetically influenced disorders increases. Because highly educated women with demanding careers are especially likely to delay parenthood, they may not realize their childbearing goals.

3.2 Prenatal Development (p. 90)

3.2 List the three periods of prenatal development, and describe the major milestones of each.

The germinal period lasts about two weeks, from fertilization through implantation of the blastocyst in the uterine lining. Structures that support prenatal growth begin to form, including the amnion, chorion, placenta, and umbilical cord.

During the period of the embryo, weeks 2 through 8, the foundations for all body structures are laid down. The neural tube forms and the nervous system starts to develop. Other organs follow rapidly. By the end of this period, the embryo responds to touch and can move.

During the period of the fetus, the organism increases rapidly in size. By the middle of the second trimester, vernix and lanugo have emerged to protect the skin. At the end of the second trimester, most of the brain’s neurons are in place.

The fetus reaches the age of viability at the beginning of the third trimester, between 22 and 26 weeks. The brain continues to develop rapidly, and new sensory and behavioral capacities emerge, including taste and odor preferences, pain sensitivity, and the ability to distinguish the tone and rhythm of different voices and sounds. Gradually the lungs mature, the fetus fills the uterus, and birth nears.

3.3 Prenatal Environmental Influences (p. 97)

3.3a Cite factors that influence the impact of teratogens, and discuss evidence on the impact of known or suspected teratogens.

The impact of teratogens varies with amount and length of exposure, genetic makeup of mother and developing organism, age of the developing organism (serious defects are most likely to occur during embryonic period), and the presence of other negative factors. Growing evidence indicates that certain teratogens exert long-term effects epigenetically.

The most widely used potent teratogenic medication is isotretinoin, a treatment for severe acne. Evidence on other common medications, such as aspirin, caffeine, and antidepressants, is mixed, and their prenatal impact is hard to separate from other correlated factors.

Babies born to users of cocaine, heroin, or methadone are at risk for a wide variety of problems, including prematurity, low birth weight, brain abnormalities, physical defects, breathing difficulties, and infant death. Lasting negative effects, however, are not well-established.

By inducing epigenetic changes that heighten sensitivity to postnatal environmental stressors, prenatal marijuana exposure may lead to long-term cognitive and emotional deficits.

Infants whose parents use tobacco are often born underweight, may have physical defects, and are at risk for long-term health, attention, learning, and behavior problems.

Maternal alcohol consumption can lead to fetal alcohol spectrum disorder (FASD). Fetal alcohol syndrome (FAS) and partial fetal alcohol syndrome (p-FAS), resulting from heavy drinking during pregnancy, involve facial abnormalities, deficient physical growth, brain damage, and substantial cognitive and behavioral impairments. In less severe forms—alcohol-related neurodevelopmental disorder (ARND) and alcohol-related birth defects (ARBD)—alcohol exposure is usually less pervasive. Self-regulation therapy for school-age children with p-FAS and ARND leads to more efficient neural functioning and gains on simple self-regulation tasks.

Prenatal exposure to high levels of ionizing radiation, mercury, PCBs, lead, and dioxins leads to physical malformations and severe brain damage. Low-level exposure has been linked to cognitive deficits and emotional and behavioral disorders. Persistent air pollution is associated with low birth weight and impaired lung and immune-system functioning.

Among infectious diseases, rubella causes wide-ranging abnormalities. Babies with prenatally transmitted HIV rapidly develop AIDS, leading to brain damage and early death. Antiretroviral drug therapy dramatically reduces prenatal transmission. Cytomegalovirus, herpes simplex 2, and toxoplasmosis can also be devastating to the embryo and fetus. Prenatal exposure to the Zika virus is associated with microcephaly and eye deformities.

3.3b Describe the impact of additional maternal factors on prenatal development.

Exercise during pregnancy is linked to improved fetal cardiovascular functioning, higher birth weight, and reduced risk of pregnancy complications.

Prenatal malnutrition can lead to low birth weight, damage to the brain and other organs, and suppression of immune system development.

Folic acid supplements can greatly reduce the risk of physical defects, premature delivery, and low birth weight. Other vitamins and minerals also have established benefits.

Severe maternal emotional stress is linked to pregnancy complications and may impair children’s capacity to manage stress, thereby elevating their risk for diverse negative behavioral outcomes and physical illnesses. Providing mothers with social support greatly reduces these consequences.

Rh factor incompatibility can lead to oxygen deprivation, brain and heart damage, and infant death.

Older mothers face increased risk of miscarriage, babies with chromosomal defects, and, after age 40, a rise in other pregnancy complications. Poor health and environmental risks associated with low income explain higher rates of pregnancy complications in adolescent mothers.

3.4 The Importance of Prenatal Health Care (p. 111)

3.4 Explain why early and regular health care is vital during the prenatal period.

Unexpected complications, such as gestational diabetes and preeclampsia, can threaten any pregnancy. Inadequate prenatal health care is common among adolescent and low-income, ethnic minority mothers, whose babies are more likely to be born underweight and to die than infants of mothers with good prenatal care. Culturally sensitive health-care practices can help overcome the barriers that discourage low-income, ethnic minority mothers from seeking care.

IMPORTANT TERMS AND CONCEPTS

age of viability (p. 95)

alcohol-related birth defects (ARBD) (p. 101)

alcohol-related neurodevelopmental disorder (ARND) (p. 101)

amnion (p. 91)

chorion (p. 93)

embryo (p. 93)

fetal alcohol spectrum disorder (FASD) (p. 101)

fetal alcohol syndrome (FAS) (p. 101)

fetus (p. 94)

germinal period (p. 91)

implantation (p. 91)

lanugo (p. 95)

neural tube (p. 94)

partial fetal alcohol syndrome (p-FAS) (p. 101)

placenta (p. 93)

Rh factor incompatibility (p. 109)

teratogen (p. 97)

trimesters (p. 94)

umbilical cord (p. 93)

vernix (p. 95)