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Abstinence-Only Education and Teen Pregnancy Rates: Why We Need Comprehensive Sex Education in the U.S. Kathrin F. Stanger-Hall1*, David W. Hall2
1 Department of Plant Biology, The University of Georgia, Athens, Georgia, United States of America, 2 Department of Genetics, The University of Georgia, Athens,
Georgia, United States of America
Abstract
The United States ranks first among developed nations in rates of both teenage pregnancy and sexually transmitted diseases. In an effort to reduce these rates, the U.S. government has funded abstinence-only sex education programs for more than a decade. However, a public controversy remains over whether this investment has been successful and whether these programs should be continued. Using the most recent national data (2005) from all U.S. states with information on sex education laws or policies (N = 48), we show that increasing emphasis on abstinence education is positively correlated with teenage pregnancy and birth rates. This trend remains significant after accounting for socioeconomic status, teen educational attainment, ethnic composition of the teen population, and availability of Medicaid waivers for family planning services in each state. These data show clearly that abstinence-only education as a state policy is ineffective in preventing teenage pregnancy and may actually be contributing to the high teenage pregnancy rates in the U.S. In alignment with the new evidence-based Teen Pregnancy Prevention Initiative and the Precaution Adoption Process Model advocated by the National Institutes of Health, we propose the integration of comprehensive sex and STD education into the biology curriculum in middle and high school science classes and a parallel social studies curriculum that addresses risk-aversion behaviors and planning for the future.
Citation: Stanger-Hall KF, Hall DW (2011) Abstinence-Only Education and Teen Pregnancy Rates: Why We Need Comprehensive Sex Education in the U.S.. PLoS ONE 6(10): e24658. doi:10.1371/journal.pone.0024658
Editor: Virginia J. Vitzthum, Indiana University, United States of America
Received March 8, 2011; Accepted August 16, 2011; Published October 14, 2011
Copyright: � 2011 Stanger-Hall, Hall. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was funded by the University of Georgia Research Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: ksh@uga.edu
Introduction
The appropriate type of sex education that should be taught in
U.S. public schools continues to be a major topic of debate, which
is motivated by the high teen pregnancy and birth rates in the
U.S., compared to other developed countries [1–4] (Table 1).
Much of this debate has centered on whether abstinence-only
versus comprehensive sex education should be taught in public
schools. Some argue that sex education that covers safe sexual
practices, such as condom use, sends a mixed message to students
and promotes sexual activity. This view has been supported by the
US government, which promotes abstinence-only initiatives
through the Adolescent Family Life Act (AFLA), Community-
Based Abstinence Education (CBAE) and Title V, Section 510 of
the Personal Responsibility and Work Opportunity Reconciliation
Act of 1996 (welfare reform), among others [5]. Funding for
abstinence-only programs in 2006 and 2007 was $176 million
annually (before matching state funds) [5,6]. The central message
of these programs is to delay sexual activity until marriage, and
under the federal funding regulations most of these programs
cannot include information about contraception or safer-sex
practices [5,7].
The federal funding for abstinence-only education expired on
June 30, 2009, and no funds were allocated for the FY 2010
budget. Instead, a ‘‘Labor-Health and Human Services, Education
and Other Agencies’’ appropriations bill including a total of $114
million for a new evidence-based Teen Pregnancy Prevention
Initiative for FY 2010 was signed into law in December 2009. This
constitutes the first large-scale federal investment dedicated to
preventing teen pregnancy through research- and evidence-based
efforts. However, despite accumulating evidence that abstinence-
only programs are ineffective [6,8], abstinence-only funding
(including Title V funding) was restored on September 29, 2009
[8] for 2010 and beyond by including $250 million of mandatory
abstinence-only funding over 5 years as part of an amendment to
the Senate Finance Committee’s health-reform legislation (HR
3590, Amendment #2786, section 2954). This was authorized by the legislature on March 23, 2010 [9].
With two types of federal funding programs available, legislators
of individual states now have the opportunity to decide which type
of sex education (and which funding option) to choose for their
state, while pursuing the ultimate goal of reducing teen pregnancy
rates. This large-scale analysis aims to provide scientific evidence
for this decision by evaluating the most recent data on the
effectiveness of different sex education programs with regard to
preventing teen pregnancy for the U.S. as a whole. We used the
most recent teenage pregnancy, abortion and birth data from all
U.S. states along with information on each state’s prescribed sex
education approach to ask ‘‘what is the quantitative evidence that
abstinence-only education is effective in reducing U.S. teen
pregnancy rates?’’ If abstinence education results in teenagers
being abstinent, teenage pregnancy and birth rates should be
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lower in those states that emphasize abstinence more. Other
factors may also influence teenage pregnancy and birth rates,
including socio-economic status, education, cultural influences
[10–12], and access to contraception through Medicaid waivers
[13–15] and such effects must be parsed out statistically to
examine the relationship between sex education and teen
pregnancy and birth rates. It was the goal of this study to evaluate
the current sex-education approach in the U.S., and to identify the
most effective educational approach to reduce the high U.S. teen
pregnancy rates. Based on a national analysis of all available state
data, our results clearly show that abstinence-only education does
not reduce and likely increases teen pregnancy rates. Compre-
hensive sex and/or STD education that includes abstinence as a
desired behavior was correlated with the lowest teen pregnancy
rates across states. In alignment with the Precaution Adoption Process
Model advocated by the National Institutes of Health we suggest
that comprehensive sex and HIV/STD education should be
taught as part of the biology curriculum in middle and high school
science classes, along with a social studies curriculum that
addresses risk-aversion behaviors and planning for the future.
Materials and Methods
Level of emphasis on abstinence in state laws Data on abstinence education were retrieved from the
Education Commission of the States [16]. Of the 50 U.S. states,
only 38 states had sex education laws (as of 2007; Table 2). Thirty
of the 38 state laws contained abstinence education provisions, 8
states did not. Following the analysis of the Editorial Projects in
Education Research Center [17], which categorizes the data on
abstinence education into four levels (from least to most emphasis
on abstinence: no provision, abstinence covered, abstinence
promoted, abstinence stressed), we assigned ordinal values from
0 through 3 to each of these four categories respectively. A higher
category value indicates more emphasis on abstinence with level 3
stressing abstinence only until marriage as the fundamental
teaching standard (similar to the federal definition of abstinence-
only education), if sex or HIV/STD education is taught (sex
education is not required in most states) [16–18]. The primary
emphasis of a level 2 provision is to promote abstinence in school-
aged teens if sex education or HIV/STD education is taught, but
discussion of contraception is not prohibited. Level 1 covers
abstinence for school-aged teens as part of a comprehensive sex or
HIV/STD education curriculum, which should include medically
accurate information on contraception and protection from HIV/
STDs [16–18]. Level 0 laws on sex education and/or HIV
education do not specifically mention abstinence.
Level of emphasis on abstinence in state laws & policies States without sex education laws may nevertheless have policies
regarding sex and/or HIV/STD education. These policies may be
published as Health Education standards or Public Education
codes [19]. These policies can also provide information on how
existing sex education laws may be interpreted by local school
boards. Information on the sex education laws and policies for all
50 US states was retrieved from the website of the Sexuality
Information and Education Council of the US (SIECUS). We
analyzed the 2005 state profiles on sex education laws and policy
data for all 50 states [19] following the criteria of the Editorial
Projects in Education Research Center [17] to identify the level of
abstinence education (Table 2). The coding for the state laws
(N = 38) and the coding for both laws and policies (N = 48) was
more or less the same for the states represented in both data sets
with 6 exceptions (Table 2): the additional information on policies
moved two states from a level 0 (abstinence not mentioned) to level
1 (abstinence covered), and four states from a level 2 abstinence
provision (abstinence emphasized) to a level 3 (abstinence stressed).
Only two states had neither a state law nor a policy regarding sex
or STD/HIV education (as of 2005): North Dakota and
Wyoming. Analyses of the two data sets gave essentially identical
results. In this paper we present the analyses of the more extensive
(48 states) law and policy data set.
Teen pregnancy, abortion and birth data Data on teen pregnancy, birth and abortion rates were retrieved
for the 48 states from the most recent national reports, which
cover data through 2005 [11,12]. The data are reported as
number of teen pregnancies, teen births or teen abortions per one
thousand female teens between 15 and 19 years of age. In general,
teen pregnancy rates are calculated based on reported teen birth
and abortion rates, along with an estimated miscarriage rate [12].
We used these data to determine whether there is a significant
correlation between level of prescribed abstinence education and
teen pregnancy and birth rates across states. The expectation is
that higher levels of abstinence education will be correlated with
higher levels of abstinence behavior and thus lower levels of teen
pregnancy.
Other factors Data on four possibly confounding factors were included in our
analyses.
Socio-economics. To account for cost-of-living differences
across the US, we used the adjusted median household income for
2006 for each state from the Council for Community and
Economic Research: C2ER [20]. These data are based on median
household income from the Current Population Survey for 2006 from the U.S. Census Bureau [21] and the 2006 cost of living index
(COLI).
Educational attainment. As an estimate of statewide
education levels among teens, we used the percentage of high
school graduates that took the SAT in 2005/2006 in each state
[22].
Ethnic composition. We determined the proportion of the
three major ethnic groups (white, black, Hispanic) in the teen
population (15–19 years old) for each state [12], and assessed
whether the teen pregnancy, abortion and birth rates across states
Table 1. U.S. teenage pregnancy and birth rates are high compared to other developed countries.
International Data U.S. France Germany Netherlands Canada UK
Pregnancy rate (2002–5) 72.2 25.7 18.8 11.8 29.2 41.3‘
Birth rate (2006) 41.9 7.8 10.1 3.8 13.3 26.7
Rates are listed as numbers per 1000 girls 15–19 years old, ‘15–18 years old [1–4]. doi:10.1371/journal.pone.0024658.t001
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were correlated with the ethnic composition of the teen
population. To account for the ethnic diversity among the teen
populations in the different states in a multivariate analysis of teen
pregnancy and birth rates, we included only the proportion of
white and black teens in the state populations as covariates,
because the Hispanic teen population numbers were not normally
distributed (see below).
Medicaid waivers for family planning. Medicaid-funded
access to contraceptives and family planning services has been
shown to decrease the incidence of unplanned pregnancies,
especially among low-income women and teens [13]. According
to the Guttmacher Institute, the national family planning program
prevents 1.94 million unintended pregnancies, including almost
400,000 teen pregnancies each year by providing millions of young
and low-income women access to voluntary contraceptive services
[13], Medicaid covered 71% of expenditures for these programs in
2006, and it is estimated that states saved $4 (associated with
unintended births) for each $1 spend on contraceptive services
[13]. Since the increasing role of Medicaid in funding family
planning was mainly due to the efforts of 21 states to expand
eligibility for family planning for low-income women who
otherwise would not qualify for Medicaid, we analyzed whether
these Medicaid waivers for family planning services (available in
some states but not in others) could bias our results. We
determined which states had received permission (as of 2005)
from the Federal Medicaid program to extend Medicaid eligibility
for family planning services to large numbers of individuals whose
incomes are above the state-set levels for Medicaid enrollment
[15]. We assessed whether the waivers (access to family planning
services) had an effect on our analysis of teen pregnancy and birth
rates across states, specifically whether they could bias our analysis
with respect to the effects of the different levels of abstinence
education.
Statistical Analyses Sample statistics. Using JMP 8 software [23], we tested all
variables for normality (Goodness of Fit: Shapiro Wilkes Test; JMP
8.0). Except for teen abortion rates and Hispanic teen population
data, all variables were normally distributed. The distribution of
the Hispanic teen population across states was not normal: most
states had relatively small Hispanic teen populations, and a few
states had a relatively large population of Hispanic teens. Teen
pregnancy and birth rate distributions included outliers, but these
outliers did not cause the distributions within abstinence education
levels to differ significantly from normal, thus all outliers were
included in subsequent analyses. For all further statistical analyses
we used SPSS [24].
Correlations. We used non-parametric (Spearman)
correlations to assess relationships between variables, and for
normally distributed variables we also used parametric (Pearson)
correlations, but these results showed the same trends and
Table 2. Abstinence provisions and levels of abstinence education in state laws & policies.
State Law: Abstinence1 Law Level2 Laws & Policy Level3
Alabama Yes 3 3
Alaska - - 1
Arizona Yes 2 3
Arkansas Yes 2 3
California Yes 1 1
Colorado Yes 2 2
Connecticut No 0 0
Delaware - - 3
Florida Yes 3 3
Georgia Yes 2 2
Hawaii - - 3
Idaho No 0 0
Illinois Yes 3 3
Indiana Yes 3 3
Iowa No 0 0
Kansas - - 0
Kentucky - - 3
Louisiana Yes 3 3
Maine Yes 1 1
Maryland - - 0
Massachusetts No 0 1
Michigan Yes 1 1
Minnesota Yes 1 1
Mississippi Yes 3 3
Missouri Yes 2 2
Montana - - 0
Nebraska - - 2
Nevada No 0 0
New Hampshire No 0 0
New Jersey Yes 1 1
New Mexico - - 3
New York - - 1
North Carolina Yes 3 3
North Dakota - - -
Ohio Yes 3 3
Oklahoma Yes 3 3
Oregon Yes 1 1
Pennsylvania Yes 2 3
Rhode Island Yes 2 3
South Carolina Yes 3 3
South Dakota Yes 2 2
Tennessee Yes 3 3
Texas Yes 3 3
Utah Yes 3 3
Vermont Yes 1 1
Virginia Yes 2 2
Washington Yes 2 2
West Virginia No 0 0
State Law: Abstinence1 Law Level2 Laws & Policy Level3
Wisconsin No 0 1
Wyoming - - -
1State laws with (yes) or without (no) an abstinence provision as of 2007 [16]. 2Level of Abstinence provision in state law as of 2007 [17]. 3Level of Abstinence provision in state law or other policy as of 2005 [19]; differences to laws2 are noted in italics.
doi:10.1371/journal.pone.0024658.t002
Table 2. Cont.
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significance levels as the non-parametric correlations. As a result,
we only report the results for the non-parametric correlations here.
Multivariate analyses. Only the two normally distributed
dependent variables were included in the multivariate analysis
(MANOVA and MANCOVA [24]): teen pregnancy and teen
birth rates. We tested for homogeneity of error variances (Levene’s
Test) and for equality of covariance matrices (Box test) between
groups. For MANCOVA we report the estimated marginal means
of teen pregnancy and birth rates (i.e. means after the influence of
covariates was removed). For pairwise comparison between
abstinence levels, we used the Bonferroni adjustment for
multiple comparisons.
Results
Among the 48 states in this analysis (all U.S. states except North
Dakota and Wyoming), 21 states stressed abstinence-only
education in their 2005 state laws and/or policies (level 3), 7
states emphasized abstinence education (level 2), 11 states covered
abstinence in the context of comprehensive sex education (level 1),
and 9 states did not mention abstinence (level 0) in their state laws
or policies (Figure 1). In 2005, level 0 states had an average (6 standard error) teen pregnancy rate of 58.78 (64.96), level 1 states averaged 56.36 (63.94), level 2 states averaged 61.86 (63.93), and level 3 states averaged 73.24 (62.58) teen pregnancies per 1000 girls aged 14–19 (Table 3). The level of abstinence education (no
provision, covered, promoted, stressed) was positively correlated
with both teen pregnancy (Spearman’s rho = 0.510, p = 0.001) and
teen birth (rho = 0.605, p,0.001) rates (Table 4), indicating that abstinence education in the U.S. does not cause abstinence
behavior. To the contrary, teens in states that prescribe more
abstinence education are actually more likely to become pregnant
(Figure 2). Abortion rates were not correlated with abstinence
education level (rho = 20.136, p = 0.415). A multivariate analysis of teen pregnancy and birth rates identified the level of abstinence
education as a significant influence on teen pregnancy and birth
rates across states (pregnancies F = 5.620, p = 0.002; births
F = 11.814, p,0.001). The significant pregnancy effect was caused by significantly lower pregnancy rates in level 0 (no abstinence
provision) states compared to level 3 (abstinence stressed) states
(p = 0.036), and level 1 (abstinence covered) states compared to
level 3 states (p = 0.005); the significant birth effect was caused by
significantly lower teen birth rates in level 0 states compared to
level 3 (p = 0.006) states, and significantly lower teen birth rates in
level 1 states compared to level 3 states (p,0.001). Socio-economic status, educational attainment, and ethnic
differences across states exhibited significant correlations with some
variables in our model (Table 4). We examined the influence of each
possible confounding factor on our analysis by including them as
covariates in several multivariate analyses. However, after accounting
for the effects of these covariates, the effect of abstinence education on
teenage pregnancy and birth rates remained significant (Figure 3).
Socio-economic status There was a significant negative correlation between median
household income (adjusted for cost of living) and level of abstinence
education (rho = 20.349, p = 0.015; Table 4), indicating a socio- economic bias at the state level on state laws and regulations with
regard to sex education. The adjusted median household income
was negatively correlated with teen pregnancy (rho = 20.383, p = 0.007) and birth (rho = 20.296, p = 0.041) rates across states: pregnancy and birth rates tended to be higher in lower-income
states. There was no correlation between household income and
abortion rates (rho = 20.116, p = 0.432). When including the adjusted median household income as a covariate in a multivariate
analysis (evaluated at $45,892), income significantly influenced teen
pregnancy (F = 5.427, p = 0.025) but not birth (F = 2.216, p = 0.144)
rates. After accounting for socioeconomic status, the level of
abstinence education still had a significant effect on teen pregnancy
(F = 4.103, p = 0.012) and birth rates (F = 10.480, p,0.001).
Educational attainment There was no significant correlation between statewide teen
education (percentage of high school graduates that took the SAT
in 2005/2006) and level of abstinence education (rho = 20.156, p = 0.291). Education was not correlated with teen pregnancy rates
(rho = 20.014, p = 0.925), but it was positively correlated with teen abortion rates (rho = 0.662, p,0.001), and as a consequence, negatively correlated with teen birth rates (rho = 20.412, p = 0.004). There was no correlation between socio-economic
status and teen educational attainment across states (rho = 20.048, p = 0.748), suggesting that these trends apply to both rich and poor
states. When including education (% graduates taking the SAT) as
a covariate in a multivariate analysis, education had a significant
influence on teen birth (F = 8.308, p = 0.006), but not on teen
pregnancy (F = 0.161, p = 0.690) rates, and after accounting for
the influence of teen education (evaluated at 39.7% of graduates
taking the SAT), the level of abstinence education still had a
significant effect on both teen pregnancy (F = 5.527, p = 0.003)
and teen birth rates (F = 10.772, p,0.001).
Ethnic composition For this analysis we focused on the three largest ethnic groups
for which data are available: white, black, and Hispanic [12]. Teen
pregnancy rates differ across these three ethnic groups. For the 48
states in this analysis, an ethnic breakdown (for all three ethnic
groups) of teen pregnancy and abortion rates was available for 26
states, and of teen birth rates for 43 states. Across this reduced
sample of states, 2005 teen pregnancy rates averaged 48.1 (61.95) pregnancies per 1000 white teens, 103.7 (65.38) pregnancies per 1000 black teens, and 141.6 (68.55) pregnancies per 1000
Figure 1. Abstinence education level prescribed in 2005 state laws or policies. All 48 states with state laws or policies on sex and/or HIV education are shown (North Dakota and Wyoming are not represented). doi:10.1371/journal.pone.0024658.g001
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Hispanic teens. Teen birth rates averaged 27.6 (61.5) births per 1000 white teens, 59.2 (62.58) births per 1000 black teens, and 96.1 (65.39) births per 1000 Hispanic teens. Abstinence education levels were positively correlated with teen birth rates in all three
ethnic groups (white: rho = 0.439, p = 0.002; black: rho = 0.328, p = 0.028; Hispanic: rho = 0.461, p = 0.001; Table 5).
Across all 48 states, abstinence education levels were signifi-
cantly correlated with the proportions of white and black teens in
the state populations (Table 4). In general, states with higher
proportions of white teens tended to emphasize abstinence less
(rho = 20.382, p = 0.007), and states with higher proportions of black teens tended to emphasize abstinence more (rho = 0.419,
p = 0.003). When we included the proportion of white and black
teens in the state populations as covariates in a multivariate
analysis (evaluated at proportion white: 0.704 and proportion
black: 0.138), only the proportion of white teens had a significant
Table 3. Teen pregnancy, abortion and birth rates (per 1000 girls aged 14–19) by level of abstinence education.
Descriptive Statistics by Abstinence Education Level 95% Confidence Interval
Outcomes Level N Median Mean Std. Error Lower Bound Upper Bound Minimum Maximum
Teen Pregnancies 0 9 57.0 58.78 4.966 47.43 70.23 33 90
1 11 57.0 56.36 3.943 47.58 65.15 40 77
2 7 61.0 61.86 3.931 52.24 71.47 50 80
3 21 76.0 73.24 2.589 67.84 78.64 47 93
Total 48 62.5 65.00 2.064 60.85 69.15 33 93
Teen Abortions 0 9 11.0 15.78 2.681 9.6 21.96 9 28
1 11 16.0 20.27 3.069 13.43 27.11 10 41
2 7 15.0 13.57 2.010 8.65 18.49 6 20
3 21 12.0 14.86 1.306 12.13 17.58 6 27
Total 48 15.00 16.08 1.096 13.88 18.29 6 41
Teen Births 0 9 35.2 34.82 3.316 22.8 41.5 18 50
1 11 26.5 28.43 1.950 24.08 32.77 19 39
2 7 40.0 39.29 2.765 32.52 46.05 31 53
3 21 49.1 47.43 2.197 42.85 52.01 30 62
Total 48 38.5 39.52 1.687 36.13 42.92 18 62
Based on 2005 data for all states except North Dakota and Wyoming, N = number of states. doi:10.1371/journal.pone.0024658.t003
Table 4. Socioeconomics and ethnic diversity as potential influences on teen pregnancy, abortion and birth rates in 48 states.
Correlation Coefficients Teen Rates per 1000 girls (14–19)
Adjusted median household income % Teens in population
1
Pregnancies Abortions Births White Black Hispanic
Abstinence Education level Spearman’s rho 0.507** 20.083 0.562** 20.349* 20.382** 0.419** 0.030
p (2-tailed) ,0.001 0.577 ,0.001 0.015 0.007 0.003 0.839
Teen Pregnancies per 1000 girls Spearman’s rho 0.329* 0.806** 20.383* 20.807** 0.597** 0.341*
p (2-tailed) 0.022 ,0.001 0.007 ,0.001 ,0.001 0.018
Teen Abortions per 1000 girls Spearman’s rho 20.221 20.116 20.564** 0.263 0.557**
p (2-tailed) 0.131 0.432 ,0.001 0.071 ,0.001
Teen Births per 1000 girls Spearman’s rho 20.296* 20.482** 0.393** 0.036
p (2-tailed) 0.041 0.001 0.006 0.806
Adjusted median income Spearman’s rho 0.298* 20.238 0.089
p (2-tailed) 0.040 0.103 0.547
% white teens in population Spearman’s rho 20.566** 20.532**
p (2-tailed) ,0.001 ,0.001
% black teens in population Spearman’s rho 20.014
p (2-tailed) 0.925
Significant correlations are marked in bold type (* significant at p,0.05, ** significant at p,0.01). 1The % teen population variables are measures of the ethnic diversity of the states. Please note the teen pregnancy, abortion and birth data (per 1000) reflect the behavior of all teens in each state: they are not limited to the behavior within that particular ethnic teen population (see Table 5).
doi:10.1371/journal.pone.0024658.t004
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effect on teen pregnancy (F = 42.206, p,0.001) and teen birth rates (F = 5.894, p = 0.020). After accounting for this influence, the
level of abstinence education still had a significant effect on teen
pregnancy (F = 2.839, p = 0.049) and teen birth rates (N = 43
states: F = 7.782, p,0.001; Figure 3).
Medicaid waivers If Medicaid waivers contribute to the positive correlation between
abstinence education and teen pregnancy at the state level, then
states with waivers should have different teen pregnancy and birth
rates than states without waivers. This was not the case. States with
waivers (N = 17) were represented across all four abstinence
education levels (Figure 4) and did not differ significantly in teen
pregnancy rates from states without waivers (N = 21, Mann
Whitney U = 237, p = 0.086), suggesting no significant effect of
waivers (at the state level) on the correlation between abstinence
levels and teen pregnancy rates. A recent study [14] found the same
level of (non-)significance (0.05,p,0.1) for the effect of waivers on teen birth rates, but reported it as significant.
Discussion
This study used a correlational approach to assess whether
abstinence-only education is effective in reducing U.S. teen
pregnancy rates. Correlation can be due to causation, but it can
also be due to other underlying factors, which need to be examined.
Several factors besides abstinence education are correlated with
teen pregnancy rates. In agreement with previous studies, our
analysis showed that adjusted median household income and
proportion of white teens in the teen population both had a
significant influence on teen pregnancy rates. Richer states tend to
have a higher proportion of white teens in their teen populations,
tend to emphasize abstinence less, and tend to have lower teen
pregnancy and birth rates than poorer states. A recent study [25]
found that higher teen birth rates in poorer states were also
correlated with a higher degree of religiosity (and a lower abortion
rate) at the state level. Medicaid waivers have previously been
shown to reduce teen pregnancy rates [13], but our analysis shows
that they do not explain our main result, the positive correlation
between abstinence education level and teen pregnancy rates.
After accounting for other factors, the national data show that
the incidence of teenage pregnancies and births remain positively
correlated with the degree of abstinence education across states:
The more strongly abstinence is emphasized in state laws and
policies, the higher the average teenage pregnancy and birth rate.
States that taught comprehensive sex and/or HIV education and
covered abstinence along with contraception and condom use
(level 1 sex education; also referred to as ‘‘abstinence-plus’’ [26],
tended to have the lowest teen pregnancy rates, while states with
abstinence-only sex education laws that stress abstinence until
marriage (level 3) were significantly less successful in preventing
teen pregnancies. Level 0 states present an interesting sample with
a wide range of education policies and variable teen pregnancy
and birth data [17–19]. For example, several of the level 0 states
(as of 2007) did not mandate sex education, but required HIV
education only (e.g. CT, WV) [19]. Only three of the level 0 states
(IA, NH and NV) mandated both sex education and HIV
education, but one of them (NV) did not require that teens learn
about condoms and contraception. This state (NV) has the highest
teen pregnancy and birth rates in that group (Figure 1). Nevada is
also one of only five states (with MD in level 0, CO in level 2, and
AZ and UT in level 3) that required parental consent for sex
education in public schools instead of an opt-out requirement that
is present in all the other states [16,19].
The effectiveness of Level 1 (comprehensive) sex education in
our nation-wide analysis is supported by Kirby’s meta-analysis of
individual sex education programs [8], Underwood et al. ’s
analysis of HIV prevention programs [27], and a recent review by
the CDC taskforce on community preventive services [28]. All
these studies suggest that comprehensive sex or HIV education
Figure 2. Mean teen pregnancy, abortion and birth rates by level of prescribed abstinence education. [Rates = numbers per 1000 girls 15–19 years old: shown are means 62 SE]. Top panel: Teen pregnancies [outliers: #28 Nevada and #29 New Hampshire]; Middle panel: Teen abortions [outlier: #32 New York]; Bottom panel: Teen births. All outliers were included in the statistical analyses. A multivariate analysis of teen pregnancy and birth rates identified the level of abstinence education as a significant influence on teen pregnancy and birth rates across states. doi:10.1371/journal.pone.0024658.g002
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that includes the discussion of abstinence as a recommended
behavior, and also discusses contraception and protection
methods, works best in reducing teen pregnancy and sexually
transmitted diseases.
Individual research studies Despite large differences between individual research studies
that evaluate specific sex education programs (e.g. sample size, approaches to sex education studied, selection of participants,
Table 5. Ethnic breakdown of teen pregnancy, birth, and abortion rates and their relationship with abstinence education, educational attainment (SAT), adjusted income and teen diversity in the states.
Correlation Coefficients for ethnic diversity in states
Pregnancy rates (per 1000 girls)
Abortion rates (per 1000 girls) Birth rates (per 1000 girls)
White Black Hispanic White Black Hispanic White Black Hispanic
Abstinence Education level Spearman’s rho 0.360 0.029 0.489* 0.024 20.166 0.005 0.463** 0.332* 0.437**
p (2-tailed) 0.071 0.890 0.011 0.909 0.417 0.980 0.002 0.030 0.003
Percent of graduates taking SAT Spearman’s rho 20.134 0.053 0.104 0.723** 0.461* 0.613** 20.450** 20.504** 20.258
p (2-tailed) 0.514 0.796 0.614 ,0.001 0.018 0.001 0.002 0.001 0.094
Adjusted median household income Spearman’s rho 20.033 0.143 0.103 20.348 20.171 20.240 20.335* 0.106 0.099
p (2-tailed) 0.873 0.486 0.617 0.081 20.404 0.238 0.028 0.500 0.529
Proportion of white teens in population Spearman’s rho 20.307 0.054 20.318 20.376 20.015 20.256 20.017 0.162 0.064
p (2-tailed) 0.127 0.794 0.114 0.058 0.944 0.206 0.916 0.298 0.685
Proportion of black teens in population Spearman’s rho 0.550** 0.539** 0.393* 0.113 0.086 0.031 0.282 0.420** 0.215
p (2-tailed) 0.004 0.004 0.047 0.584 0.675 0.880 0.067 0.005 0.166
Proportion of hispanic teens in population Spearman’s rho 20.366 20.226 0.071 0.093 0.108 0.262 20.434** 20.347* 20.140
p (2-tailed) 0.066 0.267 0.730 0.652 0.600 0.196 0.004 0.023 0.370
Sample sizes for the analysis of ethnic breakdown (for all three ethnic groups) of teen pregnancy and abortion (N = 26 states) and birth rates (N = 43 states) are limited. Significant correlations are marked in bold type (* significant at p,0.05, ** significant at p,0.01). doi:10.1371/journal.pone.0024658.t005
Figure 3. Trends in teen pregnancy and birth rates after accounting for socioeconomics, education and ethnic diversity. (A) The adjusted median household income significantly influenced teen pregnancy and birth rates, but the level of abstinence education still had a significant influence on teen pregnancy and birth rates after accounting for socioeconomic status. (B) Education had a significant influence on teen birth, but not on teen pregnancy rates. After accounting for the influence of teen education, the level of abstinence education still had a significant influence on both teen pregnancy and teen birth rates. (C) The proportion of white teens (but not black teens) in the population had a significant influence on teen pregnancy and teen birth rates. After accounting for this influence, the level of abstinence education still had a significant influence on teen pregnancy and birth rates. doi:10.1371/journal.pone.0024658.g003
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choice of control groups, types of data, control for cross-talk between students outside of class, etc.), several case studies show that abstinence-only education rarely has a positive effect on teen sexual behavior [6,8,29]. One of the few exceptions is the recent study by Jemmott et al. [30] on black middle school students in low-income urban schools: after receiving 8 hours of abstinence education as 12 year olds, significantly more students (64/95) reported to be abstinent after 24 months when compared to (control) students who received 8 hours of health education (without any form of sex education: 47/88; Fishers exact test, p = 0.037), or students who received 8 hours of safe-sex education (without an abstinence component: 41/85, Fishers exact test, p = 0.007). However, there was no significant difference in abstinence behavior between students who had received absti- nence education (64/95) and students who received 8 hours of comprehensive sex education (combining sex education with abstinence education: 57/97; Fishers exact test, p = 0.138). These two groups also did not differ in rates of reported unprotected sex (8/122 versus 8/115) or use of condoms (25/33 versus 29/37) in the previous 3 months. The abstinence-only intervention in that study was unique in that it increased knowledge about HIV/STD, emphasized the delay of sexual activity, but not necessarily until marriage, did not put sex into a negative light or use a moralistic tone, included no inaccurate information, corrected incorrect views, and did not disparage the use of condoms [30]. As a result, as pointed out by the authors, this successful version of abstinence education would not have met the criteria for federal abstinence- only funding [30]. While promoting an alternative and more effective form of abstinence education, these results also support Kirby’s findings [8] and the data in the present study that
comprehensive sex education that includes an abstinence (delay) component (level 1), is the most effective form of sex education, especially when using teen pregnancy rates as a measurable outcome.
Individual research studies also show that teaching about
contraception is generally not associated with increased risk of
adolescent sexual activity or sexually transmitted diseases (STDs)
[8] as suggested by abstinence-only advocates, and adolescents
who received comprehensive sex or HIV education had a lower
risk of pregnancy and HIV/STD infection than adolescents who
received strict abstinence-only or no sex education at all in the
U.S. and in other high-income countries [27,31].
Abstinence-only education: public opinion and associated costs
Despite the data showing that abstinence-only education is
ineffective, it may be argued that the prescribed form of sex
education represents the underlying social values of families and
communities in each state, and changing to a more comprehensive
sex education curriculum will meet with strong opposition.
However, there is strong public support for comprehensive sex
education [32]. Approximately 82% of a randomly selected
nationally representative sample of U.S. adults aged 18 to 83 years
(N = 1096) supported comprehensive programs that teach students
about both abstinence and other methods of preventing pregnancy
and sexually transmitted diseases. In contrast, abstinence-only
education programs, received the lowest levels of support (36%)
and the highest level of opposition (about 50%).
Figure 4. Teen pregnancy rates, abstinence education levels and Medicaid waivers to access family planning services. Access to waivers does not explain the difference in teen pregnancy rates (shown are means and 62 SE) in states with a different emphasis on abstinence. doi:10.1371/journal.pone.0024658.g004
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In addition to the federal and state funds spent on abstinence-
only (level 3) education, there are other costs associated with the
outcomes of failed sex education and family planning. When
deciding state policies on sex education, State legislators should
consider these additional costs. For example, based on estimates by
the National Campaign To Prevent Teen and Unplanned Pregnancy [33],
teen child bearing (compared to first birth at 20 years or older) in
the U.S. cost taxpayers (in direct and indirect costs) more than $9.1
billion in 2004.
Our data show that education (% of high school graduates
taking the SAT) was not correlated with teen pregnancy rates, but
it was positively correlated with teen abortion rates and negatively
correlated with teen birth rates. These data can be interpreted in
two ways: (1) pregnant teens who give birth are less likely to finish
high school and go on to college (i.e. pregnancy affects education).
This is supported by a recent report [34] that showed that teen
mothers are more likely to drop out of school: 51% of teen
mothers earned their high school diploma by age 22, compared to
89% of women who had not given birth as teens. (2) teens who are
motivated to go to college are not necessarily less likely to get
pregnant, but more likely to abort their pregnancies (i.e.
educational goal affects the decision of whether to carry a
pregnancy to term).
As pointed out by the Society for Adolescent Medicine, the
abstinence-only approach (as stressed by level 3 state laws and
policies and funded by the federal abstinence-only programs) is
characterized by the withholding of information and is ethically
flawed [7]. Abstinence-only programs tend to promote abstinence
behavior through emotion, such as romantic notions of marriage,
moralizing, fear of STDs, and by spreading scientifically incorrect
information [7,20,35]. For example a Congressional committee
report found evidence of major errors and distortions of public
health information in common abstinence-only curricula [36]. As
a result, these programs may actually be promoting irresponsible,
high-risk teenage behavior by keeping teens uneducated with
regard to reproductive knowledge and sound decision-making
instead of giving them the tools to make educated decisions
regarding their reproductive health [37]. The effect of presenting
inadequate or incorrect information to teenagers regarding sex
and pregnancy and STD protection is long-lasting as uneducated
teens grow into uneducated adults: almost half of all pregnancies in
the U.S. were unplanned in 2001 [38]. Of these three million
unplanned pregnancies, ,1.4 million resulted in live births, ,1.3 million ended in abortion, and over 400,000 ended in a
miscarriage [36,37] at a financial cost (direct medical costs only)
of ,$5 billion in 2002 [39].
The U.S. teen pregnancy rate is substantially higher than seen
in other developed countries (Table 1) despite similar cultural and
socioeconomic patterns in teen pregnancy rates [40]. The
difference is not due to the onset of sexual activity [1]. Instead,
the main factor seems to be sex education, especially with regard
to contraception and prevention of STDs [41]. Sex education in
Europe is based on the WHO definition of sexuality as a lifelong
process, aiming to create self-determined and responsible attitudes
and behavior with regard to sexuality, contraception, relationships
and life strategies and planning [42]. In general, there is greater
and easier access to sexual health information and services for all
people (including teens) in Europe, which is facilitated by a societal
openness and comfort in dealing with sexuality [40], by pragmatic
governmental policies [43,44] and less influence by special interest
groups.
Future Directions While states with comprehensive sex education have lower teen
pregnancy rates, even in these states rates are much higher than
seen in Europe [1]. This is likely influenced by the fact that U.S.
state laws and policies generally do not require that sex and STD
education is taught in all schools, but only provide guidelines if
local school boards decide to teach it [19]. For example, as of
August 1, 2011, only 20 states mandated sex education, and 32
states mandated HIV education in their schools [45]. In addition,
even states with comprehensive sex education laws or policies
(level 1) received federal funding for individual abstinence-only
education programs in 2005: total federal funds [19] averaged
,$14 per teen in level 1 states compared to ,$21 per teen in level 2 and 3 states [12]. An important first step towards lowering the
high teen pregnancy rates would be states requiring that
comprehensive sex education (with abstinence as a desired
behavior) is taught in all public schools. Another important step
would involve specialized teacher training. Presently the sex
education and STD/HIV curricula are often taught by faculty
with little training in this area [46]. As a further modification, ‘‘sex
education’’ could be split into a coordinated social studies
component (ethics, behavior and decision-making, including
planning for the future) and a science component (human
reproductive biology and biology of STDs, including pregnancy
and STD prevention), each taught by trained teachers in their
respective field.
As parents, educators or policy makers it should be our goals
that (1) teens can make educated reproductive and sexual health
decisions, that (2) teen pregnancy and STD rates are reduced to
the rates of other developed nations, and that (3) these trends are
Figure 5. The Precaution-Adoption-Process Model. This model offers a basis for communication and discussions between educators, scientists, sex education researchers, and health professionals, and could serve as a reference for measuring progress in sex education. In addition, it could be used as a communication tool between sex education teachers and their students [48]. doi:10.1371/journal.pone.0024658.g005
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maintained through the teenage years into adulthood. One
possibility for achieving these goals is a close alignment and
integration of sex education with the National Science Standards
for U.S. middle and high schools [47]. In addition, the Precaution Adoption Process Model (Figure 5) advocated by the National Institutes of Health [48] offers a good basis for communication
and discussions between scientists, educators, and sex education
researchers, and could serve as a reference for measuring progress
in sex education (in alignment with the new evidence-based Teen
Pregnancy Prevention Initiative). In addition, it could be used as a
communication tool between sex education teachers and their
students. It should be our specific goal to move American teens
from Stages 1 or 2 (unaware or unengaged in the issues of
pregnancy and STD prevention) to Stages 3–7 (informed decision-
making) by providing them with knowledge, understanding, and
sound decision-making skills (Figure 5). For example, a recent
study [49] attributes 52% of all unintended pregnancies (teenagers
and adults) in the U.S. to non-use of contraception, 43% to
inconsistent or incorrect use, and only 5% to method failure.
Our analysis adds to the overwhelming evidence indicating that
abstinence-only education does not reduce teen pregnancy rates.
Advocates for continued abstinence-only education need to ask
themselves: If teens don’t learn about human reproduction,
including safe sexual health practices to prevent unintended
pregnancies and STDs, and how to plan their reproductive adult
life in school, then when should they learn it, and from whom?
Acknowledgments
We thank C2ER, the Council for Community and Economic Research, for
providing additional adjusted median household income data for those
states that were not included in their online data set, and two anonymous
reviewers for helpful comments.
Author Contributions
Conceived and designed the experiments: DWH KSH. Performed the
experiments: DWH KSH. Analyzed the data: DWH KSH. Wrote the
paper: DWH KSH.
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