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Effectiveness of School-Based Teen Pregnancy Prevention Programs
in the USA: a Systematic Review and Meta-Analysis
Elliot Marseille
1
&Ali Mirzazadeh
2
&M. Antonia Biggs
3
&Amanda P. Miller
4
&Hacsi Horvath
5
&Marguerita Lightfoot
6
&
Mohsen Malekinejad
7
&James G. Kahn
5
#Society for Prevention Research 2018
Abstract
School-based programs have been a mainstay of youth pregnancy prevention efforts in the USA. We conducted a
systematic review and meta-analysis to assess their effectiveness. Eligible studies evaluated the effect on pregnancy
rates of programs delivered in elementary, middle, or high schools in the USA and Canada, published between January
1985 and September 2016. The primary outcome was pregnancy; secondary outcomes were delay in sexual initiation,
condom use, and oral contraception use. Randomized controlled trials (RCTs) and non-RCTs with comparator groups
were eligible. We developed a comprehensive search strategy, applied to major bibliographic databases, article bibliog-
raphies, gray literature, and contact with authors. We calculated risk ratios (RR) with 95% confidence intervals (CI) for
each outcome and pooled data in random effects meta-analysis. We used Grading of Recommendations Assessment,
Development and Evaluation (GRADE) to assess evidence quality. Ten RCTs and 11 non-RCTs conducted from 1984 to
2016 yielded 30 unique pooled comparisons for pregnancy, of which 24 were not statistically significant. Six showed
statistically significant changes in pregnancy rates: two with increased risk (RR 1.30, 95% CI 1.02–1.65; and RR 1.39,
95% CI 1.10–1.75) and four with decreased risk ranging from RR 0.56, 95% CI 0.41–0.77, to RR 0.75, 95% CI 0.58–
0.96. All studies were at high risk of bias, and the quality of evidence was low or very low. Identified evidence indicated
no consistent difference in rates of pregnancies between intervention recipients and controls.
Keywords Adolescent .Pregnancy .Teen pregnancy .Schools
This project was completed as part of CAPE (Consortium for Assessment
of Prevention Economics), of the NCHHSTP Epidemiological and
Economic Modeling Agreement (Grant No. U38PS004649), with the
Centers for Disease Control and Prevention. Its contents are solely the
responsibility of the authors and do not necessarily represent the official
views of the Centers for Disease Control and Prevention or the
Department of Health and Human Services.
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s11121-017-0861-6) contains supplementary
material, which is available to authorized users.
*Elliot Marseille
emarseille@comcast.net
1
Health Strategies International, 555 59th Street, Oakland, CA 94609,
USA
2
School of Medicine, Department of Epidemiology and Biostatistics,
University of California, San Francisco, CA, USA
3
Advancing New Standards in Reproductive Health (ANSIRH),
University of California, San Francisco, CA, USA
4
Philip R. Lee Institute for Health Policy Studies, University of
California, San Francisco, CA, USA
5
Philip R. Lee Institute for Health Policy Studies, Global Health
Sciences, and Global Health Economics Consortium, University of
California, San Francisco, CA, USA
6
School of Medicine, Department of Medicine, University of
California, San Francisco, CA, USA
7
Philip R. Lee Institute for Health Policy Studies, Global Health
Sciences, University of California, San Francisco, CA, USA
Prevention Science
https://doi.org/10.1007/s11121-017-0861-6
Introduction
Young people may engage in sexual behaviorthat puts them at
elevated risk for pregnancy, HIV, and other sexually transmit-
ted infections (STIs). The Centers for Disease Control and
Prevention (CDC) found in its 2013 survey of US high school
students (generally 13–19 years old) that half (47%) reported
having had sexual intercourse, including 15% with four or
more lifetime partners. About one third of students were sex-
ually active, defined as having had sex in the past 3 months.
Of these, 14% report that neither they nor their partner had
used a pregnancy prevention method at last intercourse.
Close to 300,000 young women (15–19 years old) gave
birth in the USA in 2013 (Martin et al. 2015), and over 80%
of teen pregnancies are unintended (Kost and Henshaw 2014).
Pregnancy and birth rates in adolescents have declined signif-
icantly since their peak of 61.8 per 1000 live births in 1991
and have declined every year since then (CDC 2013,2014).
The rate in the USA, 24 per 1000 live births in women aged
15–19 in 2014, is still very high when compared with other
industrialized nations, most of which have rates below 10
(World Bank 2014). There are also large disparities in rates
among socioeconomic and ethnic groups in the USA. Birth
rates in non-Hispanic black, Hispanic, and American Indian/
Alaska Native teens are approximately double those of non-
Hispanic white teens, at 4.4, 4.6, 3.5, and 2.0%, respectively
(CDC 2013).
Rationale for Systematic Review
Several systematic reviews have examined the evidence for
programs to reduce risky sexual behaviors among young peo-
ple. Most of these have focused on HIV and STI prevention
outcomes (Fonner et al. 2014; Jamil et al. 2014; Johnson et al.
2011;Kangetal.2010; Lazarus et al. 2010; Mavedzenge et al.
2014;Michielsenetal.2010;Mullenetal.2002;Naranbhai
et al. 2011; Picot et al. 2012; Shepherd et al. 2010;Underhill
et al. 2007,2008), while a few have addressed pregnancy
outcomes (Blank et al. 2010; DiCenso et al. 2002; Harden
et al. 2009; Oringanje et al. 2016; Scher et al. 2006). Some
have examined pregnancy prevention in addition to HIV and
STI prevention (Cardoza et al. 2012;Chinetal.2012;
Goesling et al. 2014; Mason-Jones et al. 2012,2016; Tolli
2012).
None of the existing reviews are designed to address our
primary research question, which is the effect of school-based
programs to reduce pregnancy in the USA. Past reviews sug-
gest that school-based programs may reduce sexual risk be-
havior in young people (Chin et al. 2012;Goeslingetal.2014;
Mavedzenge et al. 2014; Underhill et al. 2008)thoughthereis
much variation in reported effect size and high risk of bias in
many studies. Of these five review articles, only three include
pregnancy as an outcome (Chin et al. 2012;Goeslingetal.
2014; Oringanje et al. 2016). One of these, Oringanje et al.
(2016) had no country exclusion criterion and focused primar-
ily on low and middle-income countries. Studies included
school-based, community/home-based, clinic-based, and
faith-based programs, and there was no substudy for school-
based programs. Only a small number of included studies had
true control groups, and only five of the randomized con-
trolled trials (RCTs) were of school programs.
The remaining two reviews that reported on pregnancy
were confined to US programs. Of these, one is restricted to
reporting only the findings of programs with evidence of ef-
fectiveness. (Goesling et al. 2014). After applying exclusion
criteria, the authors identified 88 studies comprised of 78
unique program models (inclusion end date, January 2011).
Among these, 34 were consideredto have null findings for full
sample or subgroups and 13 had positive impacts for sub-
groups defined by sexual activity at follow-up. The authors
presented the results only for the remaining 31 programs
which had evidence of positive effect defined as one statisti-
cally significant positive impact on at least one outcome, and
no adverse effects. By excluding papers with evidence of no
effectiveness, it is impossible to critically evaluate the papers
that are included, as it is unclear whether the Bineffective^
programs lacked evidence to measure effectiveness or whether
they were actually ineffective for achieving the desired out-
comes. The third review reporting on pregnancy; Chin (2012)
focused on group-based comprehensive risk reduction and
abstinence-only programs, including both school and
community-based programs. The search period for these re-
views ended on August 31, 2007. It reached no conclusion on
abstinence-only program effectiveness. For comprehensive
programs, it found statistically significant reductions in risk
behaviors. The 11% reduction in pregnancy risk was not sta-
tistically significant. No subgroup analysis was performed on
community versus school-based programs regarding pregnan-
cy outcomes. Thus, none of the previous reviews focus spe-
cifically on the pregnancy outcomes of school-based risk re-
duction programs in the USA. In 2016 and 2017, we conduct-
ed that review, reported here. In addition, we examined the
effectiveness of these programs on three secondary outcomes:
condom use, oral contraceptive pill (OCP) use, and sexual
initiation. Our study was not powered to identify which spe-
cific approaches, e.g., service learning versus peer-led inter-
ventions, may be most effective.
Methods
Our methods are generally based on recommendations of the
Cochrane Collaboration (Higgins and Green 2011). For the
purposes of the meta-analysis, we assigned each study to
one of two broad categories: BRCT^or Bnon-RCT.^There is
some debate about whether it is defensible to include both
Prev Sci
types in the same pooled analysis. The Cochrane
Collaboration discourages this practice (Deeks et al. 2011).
However, other analysts argue that the potential problems
are exaggerated, and that in many cases, they can be combined
without introducing significant bias (Shrier et al. 2007).
Because there were frequent problems with randomization,
blinding, and other methodological issues associated with
the RCTs, the difference between non-RCTs and RCTs may
be smaller in the current analysis than in other studies. We
present results for each outcome in which non-RCTs and
RCTs are both combined and stratified. Our methods are con-
sistent with PRISMA guidelines and checklist which is avail-
able from the corresponding author (Moher et al. 2009).
Inclusion and Exclusion Criteria
To be included, studies had to report data from programs in the
USA or Canada conducted in elementary, middle, or high
schools, and report pregnancy risk for the intervention and a
control condition (another group or time). Any sexual risk
reduction intervention delivered to young people in a school
setting, including after school hours, which reports on preg-
nancy was included. We excluded interventions with one or
more components external to the school context, for which
outcomes are not stratified by component, that include young
adults or Bany age,^interventions for which outcomes are not
stratified by age range, interventions focused on secondary
prevention, not specifically addressing youth pregnancy pre-
vention outcomes, and interventions without comparators.
RCTs, prospective or retrospective observational cohorts, se-
rial cross-sectional studies, and other longitudinal analyses
published in any language were eligible. Studies in peer-
reviewed journals, reported at scientific conferences, in doc-
toral dissertations, and in other contexts were eligible. Precise
search terms are shown in the search protocol (Appendix A).
Searches and Study Selection
Using a range of keywords and Medical Subject Heading
(MeSH) terms,we developed a comprehensive search strategy
as described in our protocol (Appendix A). The date range
was from January 1, 1985 to our search date of May 17,
2017. We searched bibliographic databases including the
Cochrane Central Register of Controlled Trials
(CENTRAL), Education Resources Information Center
(ERIC), PubMed, PsycINFO, Scopus, and Web of Science.
We also searched Bgray literature^to obtain data reported
in conferences, dissertations, or other contexts outside peer-
reviewed journals. We searched the New York Academy of
Medicine’s Gray Literature Report, abstract archives of the
American Public Health Association (APHA), doctoral disser-
tations through ProQuest Dissertations, and Google and
Google Scholar using advanced targeted search syntax. We
reviewed study bibliographies and contacted authors of in-
cluded studies and other experts to learn of studies in progress
or missed.
We imported all resulting records into EndNote version X7
(Thomson Reuters 2013). One reviewer removed duplicate
records and those that were clearly irrelevant. Two reviewers
working independently then screened citations by titles, ab-
stracts, and keywords to identify records for full-text review.
A third reviewer reconciled any disagreement. Two reviewers
then examined the full text of each article to determine which
satisfied inclusion criteria.
Data Extraction
To address variations in the precise Population, Intervention
Comparator and Outcome (PICO) (Counsell 1997; Schardt
et al. 2007) scope within our systematic review, we extracted
data using an BIntervention-Outcome-Population Trio^
(IOPT) structure. Each data point describes the effect of a
specified intervention (I) on a specified outcome (O) in a
specified population (P). Because studies typically report
more than one outcome or population, we extracted multiple
IOPTs from each study. We grouped follow-up periods into
three categories: < 13, 13–23, and ≥24 months; if a study had
multiple outcomes within one period, we used the latest one.
Two reviewers working independently extracted data into a
piloted data extraction form and reconciled any discrepancies.
Extracted data included study design characteristics, study
setting, and details necessary for risk of bias assessment.
Appendix B provides a detailed description of data extraction
procedures.
Risk of Bias Assessment
We used the Cochrane Collaboration tool (Higgins et al. 2011)
for assessing risk of bias for each IOPT. For RCTs, risk of bias
in individual studies includes seven domains: sequence gen-
eration, allocation concealment, blinding of participants and
personnel, blinding of outcome assessment, incomplete out-
come data, selective outcome reporting, and other po-
tential biases. For non-RCTs, we also used indices rec-
ommended by the Grades of Recommendation
Assessment, Development and Evaluation (GRADE)
WorkingGroup(Guyattetal.2011;Holgeretal.
2013), checking whether eligibility criteria were appro-
priately developed and applied, exposures and outcomes
appropriately measured, and evaluating the adequacy of
measures to adjust for confounding and adequacy of
follow-up time. We reduced the potential for publication
bias by comprehensively searching multiple databases
and gray literature.
Prev Sci
Additional Data Inquiries
We contacted the corresponding authors of 16 of the 21 in-
cluded studies to inquire about unpublished data or subgroup
analyses pertinent to our systematic review and about any
additional studies that we may have missed. We received re-
sponses from six authors none of which led to additional or
revised effectiveness estimates.
Quality of the Evidence
We graded the quality of evidence for each IOPT following
the GRADE approach (Guyatt et al. 2011), using GRADEpro
software version 3.2 to perform analyses (Brozek et al. 2008).
GRADE ranks the quality of evidence on four levels: Bhigh,^
Bmoderate,^Blow,^and Bvery low.^Evidence quality from
RCT data is initially presumed to be Bhigh,^but can be
downgraded based on study limitations, inconsistency of re-
sults, indirectness of evidence, imprecision, or reporting bias.
Evidence quality from non-RCT study data starts Blow^but
can be upgraded if the magnitude of treatment effect is very
large, if there is a significant dose-response relation or if all
possible confounders would decrease the magnitude of an
apparent treatment effect (Guyatt et al. 2011). Evidence from
non-RCTs can also be downgraded.
Measures of Treatment Effect
We used Review Manager 5.2 (The Cochrane Collaboration
2014) provided by the Cochrane Collaboration for preparing
the review and statistical analysis. From the data extraction
file (available on request from corresponding author), we se-
lected the quantitative information required to perform the
meta-analysis. These data include sample size and risk for
both intervention and control groups, at baseline and at fol-
low-up. From these figures, we calculated the number of fa-
vorable (e.g., no pregnancy) and unfavorable (e.g., pregnancy)
events. BPregnancy^included reports by females and com-
bined male and female reports if female-only results were
not reported. These intermediate results were then used to
calculate risk ratios (RRs) and a 95% confidence interval for
each IOPT (Higgins and Green 2011)asshowninAppendix
C.
There were a few IOPTs with uncertain data needed to
calculate risk ratios; for example, the total sample size was
reported, but not the number of subjects in the control and
intervention arms. In this instance, we assumed that 50% of
the subjects were in each arm (Kirby et al. 1997a,b), an as-
sumption that is also consistent with the format of Table 1of
that paper. In another instance (Coyle et al. 2006), calculation
of an RR required an estimate of pregnancy risk in the control
group, a figure we could not derive from the paper. In our
calculation of relative risk for this IOPT, we used the highest
pregnancy risk reported in the other included studies, namely
18.5% per O’Donnell et al. (2002). This high figure would
favor detection of statistically significant benefit, and is thus
Bconservative^in the context of the preponderance of results
indicating no intervention benefit. The final figures were en-
tered into Stata® (version 13) for generation of forest plots
using Stata’s Metan command.
Pregnancy was the primary outcome of interest and was a
study inclusion criterion. Once studies had been identified, we
reviewed them for three secondary outcomes thought to be
associated with pregnancy, namely condom use, oral contra-
ceptive pill use, and sexual initiation. Secondary outcome
measures for condom use and OCP use varied somewhat.
Some studies relied on self-reported condom use at last sex,
generating a proportion across all respondents. Others report-
ed frequency of condom use over varying recall periods. We
combined these measures into one measure of relative risk of
non-condom use. Questions on OCP use were sometimes
framed as Balways use birth control^and other times as
BOCP use at last sex,^and we combined them.
Meta-Analyses
We used a random effect model because the programs studied
were diverse in design, and performed by different researchers
using different evaluation methods in varying populations.
The assumption of a fixed effect is therefore implausible
(Borenstein 2009). In addition to stratifying by RCTs and
non-RCTs, we stratified, prior to analysis, according to other
variables we hypothesized might affect outcomes: abstinence-
only and non-abstinence-only, package of activities and nar-
rowly focused activities, pregnancy reported from females
only and Bcaused pregnancy^(males) also included, analysis
of results from youth who were sexually active at baseline
only and both sexually active and inactive at baseline, and
mixed school and community setting and school setting only.
These variables are further described in Appendix D.Weused
standard funnel plot and Egger’s test methods to test for pub-
lication bias (Egger et al. 1997).
Adjustment for Baseline Values
Eight studies counted new pregnancies starting at baseline
(Coyle et al. 2006; Hawkins et al. 1999; Howard and
McCabe 1990; Kirby et al. 1997a,b; Lieberman et al. 2000;
O'Donnell et al. 2002; Smith et al. 2000). Thus, the baseline
risk of pregnancy was zero for both intervention and control
groups. For the other 13 studies, pregnancy was reported as
either as Bever^or Bany^pregnancy, so the control and inter-
vention groups could differ on prior pregnancies at baseline
(Allen et al. 1994,1997; Anderson et al. 1999; Gelfond et al.
2016; Handler 1987; Kirby et al. 1991; Kisker and Brown
1996; LaChausse 2016; Mitchell-DiCenso et al. 1997;
Prev Sci
Table 1 Summary description of 21 studies included in this systematic review and meta-analysis
Author and year Title Specific outcome Geographic
area
Urban/
rural
Design
(as assessed
by rater)
Baseline age mean (SD)
(or target age if baseline
not provided)
Baseline sex
(% female)
Allen et al. 1994 Programmatic Prevention of Adolescent
Problem Behaviors: The Role
of Autonomy, Relatedness, and Volunteer
Service in the Teen Outreach
Ever pregnant/caused
apregnancy,9–10–month
F/U (M + F combined)
Nationwide NR Exp. non-RCT
DblArm
ClusterInterventi-
on 15.7
Intervention 15.7 years
(1.3) | control 15.7
years (1.3)
Intervention
71.2% |
control
65.3%
Allen et al. 1997 Preventing Teen Pregnancy and Academic
Failure: Experimental Evaluation of A
Developmentally Based Approach
Ever pregnant, 10-month
F/U (F only)
Nationwide NR Exp. RCT DblArm
Indv.
Intervention 15.8 years
(1.13) | control 15.9
years (1.24)
100%
Anderson et al.
1999
Evaluation The Outcomes of Parent-Child
Family Life Education
Ever pregnant/caused
a pregnancy, 12-month
F/U (M + F combined)
Los Angeles
County
Urban Exp. Non-RCT
DblArm Cluster
10.6 years Intervention
58.9% |
control
62.1%
Coyle et al. 2006 All4You! A randomized trial of an HIV, other
STDs, and pregnancy prevention intervention
for alternative school students
Pregnant/caused pregnancy
since baseline, 6-month F/U
(M + F combined)
Northern CA Urban Exp. RCT DblArm
Cluster
14 years: Intervention
7.3%/control 11.3% | 15
years: Intervention
20.7%/control 27.4% |
16 years Intervention
30.7%/control 33.6% |
17 years Intervention
32.3%/control 21.8% |
18+ years: Intervention
9.1%/control 5.9%
Intervention
38.8% |
control
35.0%
Gelfond et al.
2016
Preventing Pregnancy in High School Students:
Observations From a 3-Year
Longitudinal,Quasi-Experimental Study
Pregnancy, 36-month F/U
(female only)
South Texas Rural Exp. Non-RCT
DblArm
Individual
Intervention 14.7 years (0.6)
| control 14.7
(0.6)
100%
Handler 1987 An Evaluation Of A School-Based Adolescent
Pregnancy Prevention Program
Pregnancy since baseline,
12-month F/U (F only)
Chicago,
Illinois
Urban Exp. RCT DblArm
Indv.
Targe t 12–14 years 100%
Hawkins et al.
1999
Preventing Adolescent Health-Risk Behaviors By
Strengthening Protection During Childhood
Ever pregnant/caused
a pregnancy, full intervention,
72-month F/U (M + F com-
bined)
Washington Urban Exp. Non-RCT
DblArm
Targe t 5–7 years Intervention
51.8% |
control
46.1%
Howard and
McCabe 1990
Helping Teenagers Postpone Sexual
Involvement.
Pregnancy since baseline, end
of 9th grade F/U (F only)
Atlanta,
Georgia
Urban Obs. DblArm Pros.
Cohort Indv.
Targe t 10–11 years 100%
Kirby et al. 1991 Reducing the Risk: Impact Of A New
Curriculum On Sexual Risk-Taking
Ever pregnant/caused a
pregnancy, 6-month
F/U (M + F combined)
Multiple
locations
in CA
Urban
and
Rural
Mix
Exp. Non RCT
DblArm Cluster
Targe t 14–19 years 53%
Kirby et al. 1997a An Impact Evaluation Of Project SNAPP: An
AIDS And Pregnancy Prevention Middle
School Program
Pregnancy/caused pregnancy
since baseline, 5-month F/U
(M + F combined)
Los Angeles,
California
Urban Exp. RCT DblArm
Cluster
12.3 years 54%
Kirby et al. 1997b The Impact of the Postponing Sexual
Involvement Curriculum Among Youths
In California
Pregnancy/caused pregnancy
since baseline, youth-led,
17-month F/U (M + F com-
bined)
California NR Exp. RCT DblArm
Cluster
Intervention 12.8 years |
control 12.9 years
Intervention
(55.4%) |
control
(57.3%)
Kisker and Brown
1996
Do School-Based Health Centers Improve
Adolescents’
Ever pregnant, 24–36-month
F/U (F only)
Nationwide Urban Obs. DblArm Pros.
Cohort Cluster
Targe t 14–16 years 100%
Prev Sci
Tab l e 1 (continued)
Author and year Title Specific outcome Geographic
area
Urban/
rural
Design
(as assessed
by rater)
Baseline age mean (SD)
(or target age if baseline
not provided)
Baseline sex
(% female)
Access To Health Care, Health Status and
Risk-Taking Behavior?
LaChausse 2016 A Clustered Randomized Controlled Trial
of thePositive Prevention PLUS
Adolescent PregnancyPrevention Program
Ever pregnant/caused a
pregnancy, 6-month
F/U (M + F combined)
Southern
California
Suburban Exp. RCT DblArm
Cluster
Intervention 14.63 SD
±0.50 | control 14.63
SD ±0.48
100%
Lieberman et al.
2000
Long-Term Outcomes of An Abstinence-Based
Small-Group Pregnancy Prevention
Program in New York City Schools
Pregnancy since baseline,
12-month F/U (F only)
NYC
(Bronx,
Brooklyn)
Urban Exp. Non-RCT
DblArm Indv.
ntervention 12.8% |
control 12.9%
100%
Mitchell-Dicenso
et al. 1997
Evaluation Of An Educational Program To
Prevent Adolescent Pregnancy
Ever pregnant, 48-month
F/U (F only)
Hamilton,
Ontario
Urban Exp. RCT DblArm
Cluster
Intervention 12.7 years
(0.9) | control 12.6
years (0.8)
100%
O’Donnell et al.
2002
Long-Term Reductions In Sexual Initiation and
Sexual Activity Among Urban Middle Schoolers
in the Reach for Health Service Learning Program
Pregnancy since baseline,
24-month F/U (F only)
NYC Urban Ex. RCT DblArm
Cluster
12.4 years 100%
Paine-Andrews
et al. 1999
Effects of a Replication of a Multicomponent Model
for Preventing Adolescent Pregnancy in Three
Kansas Communities
Pregnancy (EPR), F/U time
NA (F only)
Geary
County,
Kansas
Rural Obs. DblArm Pros.
Cohort Cluster
Targe t 14–17 100%
Smith et al. 2000 Students Together Against Negative Decisions (STAND):
Evaluation of A School-Based Sexual Risk Reduction
Intervention in the Rural South
Pregnancy/caused pregnancy
since baseline, 4-month
F/U (M + F combined)
Unspecified
Southern
State
Rural Exp. Non-RCT 15.6 years (0.81) Intervention
(52.4%) |
control
(49%)
Thomas et al.
1992
Small Group Sex Education at School: The McMaster
Tee n Pr o gr am
Ever pregnant/caused a
pregnancy, 48-month
F/U (M + F combined)
Hamilton,
Ontario
Urban Ex. RCT DblArm
Indv.
Intervention 12.7 years
(0.9) | control 12.6
years (0.9)
Intervention
(50.9%) |
control
(53.1%)
Vincen t et al.
1987
Reducing Adolescent Pregnancy Through School-
and Community-Based Interventions
Pregnancy (EPR 1981/2–1984
| 24-month F/U) (F only)
South
Carolina
Rural Interrupted times
series
Targe t 14–17 years 100%
Walsh-Buhi et al.
2016
The Impact of the Teen Outreach Program on Sexual
Intentions and Behaviors
Ever been pregnant, 9-month
F/U (F only)
Florida Rural Exp. RCT DblArm
Cluster
14.56 years (0.94) 100%
Author and year Baseline race/ethnicity
(% of each)
Baseline SES
(% low income; or
public assistance,
educational
attainment)
Broad description
of intervention
Dose of intervention Specific content of intervention
Allen et al. 1994 Black: interven. 40.3%/control 38.0% |
White: interven. 40.6%/control 43.3% |
Hispanic: interven. 15.2%/control
14.2% |
Other: interven. 3.9%/control | 4.5%
Mothers’mean
education level
reported on a scale 1
(did not graduate
HS)to4(college
graduate):
intervention 2.28 |
control 2.33
[Pre-existing classroom
component] +
volunteering
Volunteer activities varied
substantially in the nature
and amount of commitment
required of students.
Students engage in a range of volunteer activities provided
by facilitators working in conjunction with volunteers
from local junior leagues. Activities and time
commitment (dosage). Example activities: working as
aides in a hospital, participation in walkathons, peer
tutoring and a wide range of other types of work.
Prev Sci
Tab l e 1 (continued)
Author and year Baseline race/ethnicity
(% of each)
Baseline SES
(% low income; or
public assistance,
educational
attainment)
Broad description
of intervention
Dose of intervention Specific content of intervention
Allen et al. 1997 Black: interven. 67.7%/control
66.6% | White: interven. 17.0%/control
20.4% | Hispanic: interven.
12.9%/control 9.6% | Other: interven.
2.4%/control 3.4%
Parents’mean
education level
reported on a scale
1(didnotgraduate
HS)to4(college
graduate):
intervention 2.08 |
control 2.16
Educational peer group
meetings
+ community service
learning
+ positive adult guidance
and
support.
Meet weekly throughout
the academic year
(~ 9–10 months) plus
a minimum of 20 h of
community service learning
annually
A 9-month program that engages high school students in
community service learning weekly meetings using
TOP’s Changing Scenes curriculum, with a goal of
reducing rates of teen pregnancy, course failure, and
academic suspension. They weren’trequiredtodiscuss
sex at all. Bmaterial about sexuality was often not used^
Anderson et al.
1999
African-Am.: interven. 18.4%/control
27.3% | Hispanic: interven. 47.6%/
control 40.9% | White: interven.
15.7%/control 4.5% |Asian: interven.
6.5%/control 3% | Native Am:
interven.1.6%/control 4.5%
Mothers’education
averaged between
HS graduate and
some college.
Abstinence-based education 8 sessions. (6 sessions for early
adolescents, 1 session involved
both parents and early
adolescents; final session just for
the parents)
The RAP curriculum aims to increase student knowledge
about puberty and human reproduction, improve
communication and decision-making skills; facilitate
family communication; and delay the onset of sexual
activity. Content covers self-esteem, values, effective
communications, peer and family relationships, re-
sponsible decision making and the physical and emo-
tional changes associated with puberty.
Coyle et al. 2006 African-Am.: interven. 29%/control
25.8% | Asian
Am.:interven.16.9%/control
12.8% | Hispanic/Latino:
interven.27.6%/control 31.5% | White:
interven. 12.2%/control 12.3% | Other
or Multi-Ethnic: interven. 14.2%
interven./control 17.6%
NR Skills-based curriculum
instruction
+ service learning
14 session program (26 h total). Skills-based HIV, other STDs, and pregnancy prevention
curriculum included activities such as building
functional knowledge about HIV, other STDs,
pregnancy (through creating posters, watching videos,
playing games), clarifying students’sense of
vulnerability to HIV, other STDs, and pregnancy,
examining attitudes and beliefs about having sex and
using condoms, and building negotiation skills and
skills to use condoms correctly. In the service-learning
component, students made 5 visits as a class to volun-
teer sites including preschool/elementary schools, se-
nior centers, an organization creating a public mural,
and an AIDS service organization.
Gelfond et al.
2016
Latino: intervention 62.2%/control 62.4%
| Black (non-Latino): intervention
23.9%/control 24.5% | White
(non-Latino): intervention
13.9%/control 13.1%
63.9% low income [Pre-existing health
education] + school-based
program grounded
in BTheory of Planned
Behavior^
Treatment students received 16
sessions (25 min per session)
every year for 3 years
Need to Know (N2K) is delivered over 3 years (9th–1th
grade). Treatment students received 16 sessions
(25 min per session) every year. The ninth-grade
course, N2K: Basics, encourages self-discovery and
goal setting and discusses human growth and
development, adolescent risk behaviors,
communication, sexually transmitted infections,
abstinence, contraceptives, adolescent dating violence,
legal issues, responsible media use, refusal skills, and
role playing. The 10th-grade curriculum—N2K:
Decisions—focuses on decision-making skills, clarifies
values, promotes healthy relationships and the benefits
AL36of delaying sex, and reviews anatomy,
contraceptives, sexually transmitted infections, and
Prev Sci
Tab l e 1 (continued)
Author and year Baseline race/ethnicity
(% of each)
Baseline SES
(% low income; or
public assistance,
educational
attainment)
Broad description
of intervention
Dose of intervention Specific content of intervention
legal issues. In addition to the classroom lessons, N2K:
Decisions offers 11 BWebisodes^that add narrative to
the basic facts presented in class. Webisode 1 is viewed
together during class, and students can view the addi-
tional Webisodes The 11th-grade curriculum—N2K:
Relationships—reinforces the basic concepts taught in
9th and 10th grades. In addition, the program uses a
novel social media component in adolescent pregnancy
prevention that consists of 4 Facebook posts per lesson.
Handler 1987 Black 100% Described as Bprimarily
low income^
Multiple in and out of
school components
~ 150 h (school year 1.5 h per
week; summer three hours per
day, five days a week
for six weeks)
A school counselor and a paid community aide facilitated
this public/private partnership that included the fol-
lowing components: (1) Peer Power group project:
aimed at developing self-concept and decision-making
skills as adolescents developed a project to address
community-based problems, (2) Family Life
Education: a supplemental and comprehensive sexual-
ity education program, (3) intergenerational support:
including parents and/or adult volunteers to help with
projects, (4) Exposure to contraceptive/health services:
field trips and guest speakers, (5) Exposure to career
opportunities: trips and guest speakers, and (6)
Enrichment Activities: field trips to cultural events.
This program was evaluated during its first year of
implementation, and much of the planned intervention
was not fully implemented (Scher 2006)
Hawkins et al.
1999
White: interven. 45.6% | control 45.6% Low SES. % Eligible
for free lunch:
intervention 56.4% |
control 55.8%
Developmentally-adjusted
social competence training
+ parent/teen education
Received intervention in Grades 1
through 6
Classroom instruction and management Teachers receive
5 days of in-service training a year that cover 3 major
components: proactive classroom management; inter-
active teaching and cooperative learning. Child Skills
Development—1st grade teachers receive instruction in
the use of a cognitive and social skills training curric-
ulum. This curriculum develops children’s skills for
involvement in cooperative learning groups and other
social activities without resorting to aggressive or other
problem behaviors. In sixth grade, students receive 4 h
of training from project staff in skills to recognize and
resist social influences to engage in problem behaviors
and suggest positive alternatives to stay out of trouble
while keeping friends). Parent Intervention—Parent
training classes appropriate to the developmental level
of the children were offered on a voluntary basis
through the intervention to parents and adult caregivers.
1st/2nd grade: parents were offered training in child
Prev Sci
Tab l e 1 (continued)
Author and year Baseline race/ethnicity
(% of each)
Baseline SES
(% low income; or
public assistance,
educational
attainment)
Broad description
of intervention
Dose of intervention Specific content of intervention
behavior management skills through a 7 session cur-
riculum called BCatch em being good^. 2nd/3rd grade
parents were offered a 4 session curriculum called
BHow to help your child succeed in school^. 5th/6th
grade parents were offered to participate a 5 session
curriculum, BPreparing for the Drug (Free) years
Howard and
McCabe 1990
Black 99% Low income [Pre-existing standard
sex education]
+ PSI education and
outreach
BSocial inoculation
model^
10 period program is presented
each year to all 8th grade
student.
Postponing Sexual Involvement program primarily
focuses on the social and peer pressures that lead young
people into early sexual involvement and on ways to
resist such pressures. The emphasis is on why young
people are having sex, and how they might avoid it,
rather than on consequences of behavior. Each of the 5
classroom period sessions concentrate variations of a
single message—how and why to postpone sexual
involvement. Material is presented by older, socially
successful students.
Kirby et al. 1991 White 62% | Latino 20% | Asian 14%
| Black 2% | Native American 2%
Mothers’education
level 74% had
graduated high
school and 47% had
attended college.
[Pre-existing health
education w/ sex
education component] +
sexuality education curric-
ulum based on social
learning theory, social in-
oculation
theory and cognitive be-
havioral theory
15 class sessions (~ 3 weeks) Curriculum uses the concepts of social learning theory,
social inoculation theory and cognitive behavioral
theory as they might respectively apply to pregnancy
prevention in teens. It also tries to facilitate
communication between parents and teens
Kirby et al. 1997a Latino 64% | Asian 13% | African-
American 9% | Non-Latino white 5%
NR Peer-led sex education
curriculum based
on social learning theory.
8 sessions delivered over a 2 week
period.
SNAPP incorporated principles of social learning theory
by providing multiple opportunities for students to
recognize social influences, and to observe and practice
assertive communication and resistance skills. Students
practiced modeling effective refusal skills through role
playing, and also practiced giving counter-arguments to
common reasons to have sex or not to use a condom.
SNAPP program also incorporated principles of the
health belief model by striving to increase Youths’
perceived susceptibility to pregnancy and HIV through
selected activities. Program messages were conveyed
using a variety of engaging Bhands on^activities such
as games, role plays, large-and small group activities,
guided discussion, and answer sessions.
Kirby et al. 1997b Black: interven. 9.8%/control 10.1% |
White: interven. 21.2%/control 20.7% |
Hispanic: interven. 46.4% | control
48.9%
Mothers’mean
education level
reported on a scale
1(8thgradeorless)
[Pre-existing standard
sex education]
+ PSI program
5sessions(45–60 min in length). #
of hours of standard sex
education NR. PSI for parents is
asingle90–120 min session.
Students attend the youth-led PSI program which consists
of 5 Sessions. Session I focuses on the risks of early
sexual involvement and helps youths explore the rea-
sons that teenagers have sex and the reasons why they
Prev Sci
Tab l e 1 (continued)
Author and year Baseline race/ethnicity
(% of each)
Baseline SES
(% low income; or
public assistance,
educational
attainment)
Broad description
of intervention
Dose of intervention Specific content of intervention
| Asian/Pacific Islander: interven.
8.4%/control 7.5% | American Indian:
interven. 4%/control 3.6%
| Other: interven. 8.1%/control 6.9%
to 5 (college
students):
intervention 2.8 |
control 2.8
might choose to wait. Session II helps young people
understand and resist the social pressures that can lead
to early sexual involvement. Session III identifies peer
pressures that can affect teenagers’sexual behavior and
helps teenagers determine their own limits for physi-
cally expressing affection. Session IV teaches assertive
responses to help teenagers resist pressure to engage in
sex. Session V provides reinforcement of the material
learned in previous sessions. The PSI intervention in-
cluded class discussions, group activities, use of videos
or slides and a small amount of role playing. PSI for
parents (companion intervention with parents of stu-
dents in PSI). Single session to help parents reinforce
their children learning experiences regarding postpon-
ing sexual involvement.
Kisker and Brown
1996
NR NR [Pre-existing health
services--likely
varied] + access to a
school
health center (these also
varied
in content/services)
Continuous access Student health centers located at the schools. Services
varied but in all but two sites psychosocial services to
students available with parental consent. Other
services: Treatment and referral for acute illness,
pregnancy, injuries and STDs; routine screening and
preventative care (physical examinations,
immunizations and vision screenings; and care for
chronic diseases and disorders. Some offered HIV
Testing, prenatal care, dental care and hearing
screening.
LaChausse 2016 White: intervention 34%/control
38.% |Black: intervention
18%/control 18%
| Asian: intervention 8%/control 9% |
Hispanic: intervention
74%/control 73% (exceeds 100%)
NR Classroom-based abstinence
plus education
11 sessions, 45 min each Positive Prevention PLUS is an 11 lesson curriculum
developed for 9th–12th graders. The 11-lesson curric-
ulum includes lessons on the benefits of abstinence,
assertive communication, refusal skills, accessing re-
productive health services, condom negotiation, and
condom use. Students practice communication about
abstinence and risk reduction skills through scripted
role play and other interactive activities
Lieberman et al.
2000
Black/Caribbean: interven. 70.3%/control
62.7% | Hispanic:
interven. 19.8%/control 23.5% | Other:
interven. 9.9%/control 13.8%
NR Abstinence-based education 12–14 sessions over one semester
(each session lasts for one class,
35–45 min)
Project IMPPACT staff are invited by classroom and
physical education teachers to make presentations to
students, during which they describe the program and
invite students to join a small group. Students
self-select into the groups and are required to obtain
parental permission. The small group is the essential
component of Project IMPPACT. This approach differs
from more traditional classroom—based sex education,
in that group discussions guided by a trained and
trusted adult help young people incorporate new ideas
Prev Sci
Tab l e 1 (continued)
Author and year Baseline race/ethnicity
(% of each)
Baseline SES
(% low income; or
public assistance,
educational
attainment)
Broad description
of intervention
Dose of intervention Specific content of intervention
and openly discuss with their peers the issues they face
as teenagers. Small groups that provide knowledge and
life-skills building activities have been shown to work
well for Youth in a variety of settings. The Project
IMPPACT groups work to build communication skills,
support healthy adult-child and peer communications,
and attempt to create peer groups in which new be-
havior patterns become acceptable and desirable.22
Furthermore, the experience is meant to enhance young
people’s ability to adopt or reject new ways of thinking
by providing the opportunity to question and apply new
information through guided interaction with significant
others—i.e., people whose opinions matter, such as
peers or a respected adult.
Mitchell-Dicenso
et al. 1997
NR NR McMaster Teen Program
(small
group classroom
education}
10 one-hour sessions Program Objectives: to provide adolescents with accurate
information about the male/female reproductive sys-
tems and adolescent development; to offer strategies for
developing responsible relationships; to assist adoles-
cents in communicating their thoughts and feelings; to
help them learn to use systematic problem-solving
skills in decision-making related to their sexual activi-
ty; and to enable adolescentstopracticeimplementing
their decisions. The small groups were led by 63 tutors
who included public health nurses, elementary school
physical/health education teachers, community profes-
sionals who had been practicing public health nurses.
The MTP was co-educational and offered in small
groups. The MTP also included an opportunity for
students to learn and practice problem-solving and
decision-making skills around sexual activity. Tutors
for the MTP program were also given specific prepa-
ration to ensure their comfort in discussing the topic.
O’Donnell et al.
2002
African-American (71%)
| Latino (26%)
Described as
coming from
Beconomically
disadvantaged^
backgrounds
[Pre-existing RFH classroom
component] + service
learning
90 h (3 h per week for 30 weeks
which is one academic year)—
students were tracked for 4
academic years
The RFH CYS intervention is a structured service lea rning
program that combines community field placements
with classroom health instruction. During the school
year, RFH CYS students spend about 3 h each week
providing service in community settings, including
nursing homes, senior centers, full-service clinics, and
child day care centers. Back in their health classes,
students share their experiences in debriefing sessions
that are used to reinforce critical skills. Classroom time
is therefore provided for students to make observations,
pose questions, and analyze their experiences as a way
Prev Sci
Tab l e 1 (continued)
Author and year Baseline race/ethnicity
(% of each)
Baseline SES
(% low income; or
public assistance,
educational
attainment)
Broad description
of intervention
Dose of intervention Specific content of intervention
to put theirservice experience into an appropriate con-
text
Paine-Andrews
et al. 1999
GEARY COUNTY: White 66%
| Black 23% | Hispanic 6% |
Asian 4% | small numbers of
Native American residents as
well.—WICHITA: BLow income
neighborhood,^may = Bmostly
black and Latino.^
Lower-middle class.
Geary: median
income $24 K
(1990 dollars) |
Wichita, BLow
income.^
School/Community Sexual
Risk Reduction
Replication
Initiative
Paper reports number of instruction
hours but unclear if these are
hours attended by respondents at
follow-up.
Multi-component community-based structural interven-
tion. Mostly quite vague. The clearest thing is this:
Bextension of school-linked clinic hours to accommo-
date student schedules and support groups established
in middle schools/^Apart from that, BThe primary
components were enhanced sexuality education for
teachers and parents; comprehensive, age-appropriate
sexuality education from kindergarten through 12th
grade (K–12); increased access to health services; col-
laboration with school administrators; use of the mass
media; increased awareness and involvement of the
entire community in teenage pregnancy prevention;
peer support and education; alternative activities for
young people; and involvement of the faith
community.^BThe primary focus of the project was on
healthy choices for youth and families. Staff and vol-
unteers placed great emphasis on alternative activities
(especially after school and during summer breaks and
school holidays), peer-support groups for both males
and females, sexuality education in the community for
youth and parents, life-options programs (such as
mentoring, tutoring and peer leadership), and media
attention to problems and solutions associated with
adolescent pregnancy.^
Smith et al. 2000 Black: interven. 71%/control 53% |
White (non-Hispanic): interven.
29%/control 43% | Other: interven.
0%/control 4%
NR [Pre-existing traditional
sex education
class] + STAND Peer
Educator
Training program
36 h (5-h team building the
first week and then meet
2haweekfor15weeks)
STAND is designed to promote abstinence and reduce
sexual risk for those who do not abstain. It also seeks to
encourage participants to influence their peers so as to
change the cultural norms of their community to
decrease the social acceptability of sexual risk taking.
Instruction includes games, simulations, role-play
mini-lectures, video clips, small group discussions,
skills practice with verbal feedback and coaching,
contraceptive demonstrations, a visit to the local health
dept., locating contraception in local stores, calling a
national hotline an anonymous question box, visits
from an AIDS specialist physician and a public health
nurse and optional parent/teen activities
Thomas et al.
1992
Described as BMulti-ethnic^Blue-collar School-based education 10 1-h sessions held over 6–8-week
period
The McMaster Teen Program is a primary prevention
program based on the cognitive-behavioral model for
preventing unwanted pregnancy. Components of the
program include films, group discussion, role play,
Prev Sci
Tab l e 1 (continued)
Author and year Baseline race/ethnicity
(% of each)
Baseline SES
(% low income; or
public assistance,
educational
attainment)
Broad description
of intervention
Dose of intervention Specific content of intervention
Q&A periods addressing relevant topics such as normal
adolescent development, the influence of peer pressure
on behavior, gender roles, responsibility in
relationships, stages of physical intimacy, teenage
pregnancy and childbearing. A unique aspect of the
program was the use of small coeducational tutor-led
groups. Tutors included public health nurses, elemen-
tary school physical/health education teachers, and
community professionals who had been practicing
public health nurses (PHNs) or teachers.
Vincen t et al.
1987
Black 58% | White 42% Low income; ~ 60% of
parents without high
school diploma
School/community programs Continuous access Education of parents, teachers and school administrators
throughclasseswhichisthenintegratedinschool
curriculum (and within community). While there is no
Bsex education^course per se, the basic tenets of the
intervention program/classes are integrated in all grades
(K-12) within all subject areas. Outreach and training
of parents, clergy; the community organizations; radio
and newspapers
Walsh-Buhi et al.
2016
White: intervention 59.1%/control
61.3% | Hispanic/Latino: intervention
20.6%/control 19.7% | Black:
intervention 11.3%/control 9.9% |
Other: intervention 9.0%/control 9.1%
NR Health opportunities through
physical education
(HOPE)
classroom plus communi-
ty
service learning
25 sessions delivered
over 9 months
Teen Outreach Program (TOP) uses weekly educational
group sessions, CSL, and positive adult guidance to
help youth build healthy behaviors, life skills, and a
sense of purpose. The curriculum incorporates topics
such as goal setting, communication/assertiveness,
sexuality, and human development. The sexuality
component is woven into a larger, asset-focused pro-
gram model. The curriculum also features a CSL Guide
that provides structured exercises to identify commu-
nity needs and brainstorm/choose service project ideas
(which are youth selected). Flexible in nature, TOP can
be implemented in school settings, after-school
programs, or within community organizations. As
intended, TOP should be implemented over 9 consec-
utive months with a minimum of 25 weekly sessions.
Prev Sci
Paine-Andrews et al. 1999; Thomas et al. 1992; Vincent et al.
1987; Walsh-Buhi et al. 2016). To correct for these baseline
differences, we used the pregnancy risk difference between
intervention and control groups at baseline to adjust the
post-intervention risk of pregnancy in controls, and then com-
pared post-intervention risk of pregnancy in the intervention
group to this adjusted risk in the control group.
Results
Search Results
Our searches yielded 4867 unique citations, including 94 in
the gray literature (Fig. 1). Screening of titles and abstracts
identified 222 citations for full-text review, of which 21 ulti-
mately met inclusion criteria and proceeded to data extraction.
See Appendix E for details on exclusion, by study. Key infor-
mation on the 21 included studies is shown in Table 1.Ten
(48%) were RCTs, and 11 (52%) were non-RCTs. Five (24%)
were set in rural areas, 11 in urban, 1 in suburban, one in
mixed urban-rural settings, and three were indeterminate.
These studies were conducted in eight states, one was con-
ducted in Ontario, Canada, one was conducted in unspecified
Bsouthern states,^and two had Bnationwide^scope. The 13
(62%) studies from which we could extract SES information
indicated low income or low educational levels, and these
terms are defined in various ways. For example, low SES is
defined using specific tangible criteria such as Beligible for
free lunch in one study^(Hawkins et al. 1999)andBpaid less
than standard low-income fee at last hospital visit^(Howard
and McCabe 1990). Other studies classified the target popu-
lation as low SES based on broad terms such as Beconomically
disadvantaged^(O’Donnell et al. 2002), Bblue collar^
(Thomas et al. 1992), and Bprimarily low income^(Handler
1987). By contrast, five studies that provided information on
educational attainment consistently defined it in specific, mea-
surable terms such as mean educational level reported on a
scale from Bdidn’t graduate high school, to Bcollege graduate^
(Allen et al. 1994)orBmother’s finished high school: 74%;
finished college 47%^(Kirby et al. 1991). As shown in
Tab le 1, the average age (or targeted age when actual
age was not reported) of study subjects at baseline was
as low as 10.6 years old in one abstinence-only based
program in Los Angeles County, four others had an
average age of 12, and the rest ranged from 14 to
17 years old. The study population was disproportion-
ately African-American and Hispanic, except for one
curriculum-based sexuality education program in multi-
ple California settings that was 62% white (Kirby et al.
1991). Two studies had 99–100% African-American
subjects (Handler 1987; Howard and McCabe 1990).
Records idenfied through database
searching (Cochrane Central Register of
Controlled Trials, ERIC, Pubmed, PsycINFO,
SCOPUS, Web of Science)
(n =4,867)
Screenin
g
Included Eligibility Idenficaon
Addional records idenfied through search
of APHA, ProQuest, NY Academy of
Medicine, and target searches of key orgs
(using Google syntax)
(n = 94)
Records aer duplicates removed
(n = 4,113)
Records screened based
on tle and abstract
(n = 4,113)
Records excluded
(n = 3,891)
Full-text arcles assessed
for eligibility
(n = 222)
Full-text arcles excluded,
with reasons
(n = 201)
Studies included in
quantave synthesis
(meta-analysis)
(n = 21)
Fig. 1 Flowchart for systematic
review. From: Moher et al.
(2009). Preferred Reporting Items
for Systematic Reviews and
Meta-Analyses: The PRISMA
Statement. PLoS Med 6(7),
e1000097. https://doi.org/10.
1371/journal.pmed1000097
Prev Sci
Two (10%) of the studies evaluated abstinence-only pro-
grams. As shown in the right-hand column of Table 1,the
remaining 19 included a wide range of education modalities,
including service learning, positive youth development, peer-
led programs, and other pedagogical models including cogni-
tive behavioral theory and social learning theory. These cate-
gories overlap, and we are aware of no definitive typology for
characterizing school-based risk reduction programs.
Risk of Bias in Included Studies
Overall, risk of bias was high in our included studies. Among
RCTs, randomization methods were poor in one study (Allen
et al. 1997) and unclear in five (Handler 1987; Kirby et al.
1997a; LaChausse 2016; O'Donnell et al. 2002; Walsh-Buhi
et al. 2016). No trials were blinded to participants, personnel,
or outcome assessors as this is infeasible in a school-based
study. Allocation concealment in RCTs was either not done
(Handler 1987; Kirby et al. 1997b; Thomas et al. 1992; Walsh-
Buhi et al. 2016) or was not reportedclearly (Allen etal. 1997;
Coyle et al. 2006; Kirby et al. 1997a; Mitchell-DiCenso et al.
1997;O’Donnell et al. 2002). Four RCTs (Coyle et al. 2006;
Kirby et al. 1997a; O'Donnell et al. 2002;Thomasetal.1992)
and three non-RCTs (Gelfond et al. 2016; Kirby et al. 1991;
Lieberman et al. 2000) lost more than 20% of participants at
follow-up, placing them at high risk of attrition bias. We
suspected selective outcome reporting in two studies: one ex-
cluded certain sites from analysis (Allen et al. 1997) and one
excluded 6% of responses as Bincompatible^as well as par-
ticipants who did not complete follow-up surveys (Kirby et al.
1997b). Among non-RCTs, two were at high risk of bias be-
cause the SES characteristics of study groups lacked baseline
equivalence (Howard and McCabe 1990; Smith et al. 2000).
Four of the 21 studies had high risk of contamination from the
control group, thereby biasing the estimated intervention ef-
fects toward null (Kisker and Brown 1996; Lieberman et al.
2000; Paine-Andrews et al. 1999; Smith et al. 2000). Seven of
the 21 studies did not adjust outcomes for confounding
(Anderson et al. 1999;Handler1987; Hawkins et al. 1999;
Howard and McCabe 1990; Lieberman et al. 2000; Smith
et al. 2000; Vincent et al. 1987). Outcome adjustment was
unclear in five studies (Kirby et al. 1991,1997a;Mitchell-
DiCenso et al. 1997; O'Donnell et al. 2002; Thomas et al.
1992). The Egger’s test for small-study effects and funnel plot
asymmetry suggested no publication bias. Pvalues were 0.53,
0.81, and 0.06 for results at < 13, 13–24, and 24+ months,
respectively (details on risk of bias for each IOPT and funnel
plots are available on request from corresponding author).
Meta-Analysis Results
The 21 included studies generated 28 pregnancy RR study-
level IOPTs, which fell into one of the three follow-up periods
(12 < 13 months, 6 13–23 months, and 10 ≥24 months). The
studies also provided 22, 15, and 11 computable study-level
RRs for Bno sexual initiation,^Bno condom use,^and Bno
OCP use,^respectively. Our results are presented in forest
plots in Fig. 2for pregnancy risk and in Appendix F for sec-
ondary outcomes. Results stratified by selected variables are
presented in Table 2for pregnancy riskand in Appendix G for
secondary outcomes. Meta-analysis results with statistically
significant pooled findings are summarized in Table 3,and
discussed below.
Primary Outcome—Pregnancy
Stratification by Follow-Up Period Only Our analysis yielded
a RR for pregnancy of 0.82 (95% CI 0.63–1.29), 1.3
(95% CI 1.02–1.65), and 0.96 (95% CI 0.81–1.13), for
<13, 12–23, and ≥24 months of follow-up, respectively
(Fig. 2). The result for 12–23 months thus just crossed
the threshold of statistical significance for increased risk
of pregnancy. Individual study IOPTs with statistically
significant results were Allen et al. (1994,1997)for<
13-month follow-up (reduced pregnancy risk), Kirby
et al. (1997b)for13–24 months (increased risk), and
Hawkins et al. (1999) (full intervention) for ≥24 months
of follow-up (reduced risk).
Stratification by Follow-Up Period and by Study and Program
Features Table 2shows the 36 pooled results for the
three follow-up periods and seven intervention or study
features that could plausibly be correlated with a finding
of program outcomes in pooled results. (Five pooled
results appear two or three times in Table 2,thusonly
30 unique results). Broadly, the pooled outcomes did
not show a statistically significant effect on pregnancy
risk, and this is true for both the RCTs and non-RCTs
considered separately. The six pooled results stratified
by follow-up period and intervention or study features
with statistically significant estimates include two with
increased pregnancy risk and four with decreased risk
(Tables 2and 3).
Secondary Outcomes—
Sexual Initiation, Condom Use,
and OCP Use
Sexual Initiation One of the pooled results showed a sta-
tistically significant outcome when stratified by the
three follow-up periods only (Appendix F). At < 13-
month follow-up, the pooled risk ratio was 0.87 (95%
CI 0.78–0.97); however, this result was not apparent in
the other two follow-up periods, 0.99 (95% CI 0.88–
1.10) and 0.95 (95% CI 0.90–1.01) for 13–24 and
24 months+, respectively. Six of 21 unique study or
program-type pooled comparisons were statistically
Prev Sci
significant, with point estimate RRs between 0.80 (95%
CI 0.66–0.99) and 0.93 (95% CI 0.88–0.98) (Table 3
and Appendix G).
Condom Use The pooled risk reduction for the < 13-month
follow-upperiodshowedastatistically significant effect,
0.84 (95% CI 0.75–0.95); however, the studies for which we
could calculate a risk reduction ration for the 13–24-month
period showed no statistically significant benefit 1.04 (95%
CI 0.92–1.18) showed a statistically significant outcome when
stratified by the three follow-up periods only (Appendix F).
Of 19 unique pooled results by study or intervention charac-
teristics, 4 were statistically significant and showed decreased
risk, ranging from RR 0.79 (95% CI 0.62–0.95) to 0.86 (95%
CI 0.75–0.98) (Table 3and Appendix G).
OCP Use None of the pooled results showed a statistically
significant outcome when stratified by the three follow-up
periods only (Appendix F). Of nine unique pooled results by
study or intervention characteristics, only one was statistically
significant, with increased risk, RR 1.12 (95% CI 1.02–1.22)
(Table 3and Appendix G).
Quality of the Evidence: GRADE Results
Overall, low to very-low-quality evidence suggests that
school-based pregnancy prevention programs have no effect
in reducing pregnancy rates in adolescents in the USA. The
GRADE analysis is detailed in Appendix H, and summarized
below. In evidence from RCTs, four trials contributing very-
low-quality evidence found no difference in reported pregnan-
cies at times ranging from 5 to 12 months (Allen et al. 1997;
Coyle et al. 2006;Handler1987; Kirby et al. 1997a). Evidence
quality for this outcome was graded down for very serious risk
of bias (among other issues, no trial was blinded and random-
ization methods were poor), serious inconsistency (wide range
in point estimates, no trial achieved statistical significance),
and serious imprecision (few outcome events). In six trials
with longer follow-up, negative findings and evidence quality
were similar. The longest trials had a low (not very low) evi-
dence rating. Quality of the evidence from the non-RCTs was
similar. Four studies provide very-low-quality evidence for no
effect at 6 to 12 months (Allen et al. 1994; Howard and
McCabe 1990; Kirby et al. 1991;Smithetal.2000).
Evidence quality was graded down for serious risk of bias
Fig. 2 Forest plot of meta-analysis results for pregnancy risk ratio using random-effects model
Prev Sci
Table 2 Meta-analysis results of pregnancy incidence, stratified by selected variables
Outcome IOPTs Events, treatment Event, control Risk ratio (95% CI)
1. Program type (abstinence only and comprehensive programs)
1.1 < 13 months; abstinence only 2 6/140 5/131 1.15 (0.36 to 3.67)
1.2 < 13 months; comprehensive 10 190/6291 208/5638 0.81 (0.61 to 1.09)
1.3 13–23 months; comprehensive 6 201/5089 135/4944 1.3 (1.02 to 1.65)
1.4 24+ months; comprehensive 10 770/5262 414/3375 0.96 (0.81 to 1.13)
2. Study type (RCTs and non-RCTs)
2.1 < 13 months; RCT 5 102/3301 100/2494 0.79 (0.50 to 1.25)
2.2 13–23 months; RCT 5 145/4660 102/4615 1.29 (0.94 to 1.79)
2.3 24+ months; RCT 3 225/1948 118/1090 0.99 (0.66 to 1.49)
2.4 < 13 months; observational 7 94/3130 113/3275 0.85 (0.59 to 1.24)
2.5 13–23 months; observational 1 56/429 33/329 1.3 (0.87 to 1.95)
2.6 24+ months; observational 7 545/3314 296/2285 0.93 (0.76 to 1.12)
3. Single interventions and intervention packages
3.1 < 13 months; single interventions 10 151/5979 165/5371 0.82 (0.63 to 1.09)
3.2 13–23 months; single interventions 5 178/4946 118/4850 1.39 (1.1 to 1.75)
3.3 24+ months; single interventions 7 721/4059 348/2127 0.99 (0.83 to 1.21)
3.4 < 13 months; intervention package 2 45/452 48/398 0.7 (0.26 to 1.9)
3.5 13–23 months; intervention package 1 23/143 17/94 0.89 (0.5 to 1.57)
3.6 24+ months; intervention package 3 49/1203 66/1248 0.78 (0.54 to 1.12)
4. Adult led and peer led
4.1 < 13 months; adult-led 9 174/5541 199/4974 0.75 (0.58 to 0.96)
4.2 13–23 months; adult-led 4 163/3576 112/3427 1.25 (0.99 to 1.57)
4.3 24+ months; adult-led 10 770/5262 414/3375 0.96 (0.81 to 1.13)
4.4 < 13 months; peer-led 3 22/890 14/795 1.51 (0.68 to 3.33)
4.5 13–23 months; peer-led 2 38/1513 23/1517 1.47 (0.51 to 4.2)
5. Strictly school-based and mixed school-community settings
5.1 < 13 months; strictly school-based 7 135/3672 100/2695 1.04 (0.76 to 1.44)
5.2 13–23 months; strictly school-based 6 201/5089 135/4944 1.3 (1.02 to 1.65)
5.3 24+ months; strictly school-based 6 717/4001 337/2069 1.03 (0.87 to 1.22)
5.4 < 13 months; school-community 5 61/2759 113/3074 0.56 (0.41 to 0.77)
5.5 24+ months; school-community 4 53/1261 77/1306 0.72 (0.51 to 1.01)
6. Pregnancy (female only) and pregnancy plus caused pregnancy (male + female)
6.1 < 13 months; female only 5 37/1971 64/2212 0.59 (0.39 to 0.89)
6.2 24+ months; female only 8 678/4870 306/2963 0.99 (0.83 to 1.20)
6.3 < 13 months; female plus male 7 159/4460 149/3557 0.94 (0.67 to 1.34)
6.4 13–23 months; female plus male 6 201/5089 135/4944 1.3 (1.02 to 1.65)
6.5 24+ months; female plus male 2 92/392 108/412 0.84 (0.52 to 1.36)
7. Pregnancy; sexual experience at baseline (experienced and inexperienced)
7.1 < 13 months; experienced and inexperienced 10 160/6261 192/5632 0.73 (0.57 to 0.64)
7.2 13–23 months; experienced and experienced 5 178/4946 118/4850 1.39 (1.1 to 1.75)
7.3 24+ months; experienced and inexperienced 10 770/5262 414/3375 0.96 (0.81 to 1.13)
7.4 < 13 months; experienced only 5 53/563 32/429 1.24 (0.83 to 1.85)
7.5 13–23 months; experienced only 3 40/554 31/429 0.94 (0.61 to 1.47)
Statistically significant results in italics. Some pooled comparisons appear in multiple categories; Risk Ratio < 1 favors intervention
Prev Sci
and serious imprecision. In one study assessing outcomes at
18 months, there was also no difference in pregnancies (Kirby
et al. 1991).
Discussion
We undertook a systematic review and meta-analysis of as-
sessments of the specific effect of school-based programs in
the USA to reduce pregnancy in adolescents among programs
that measured pregnancy as an outcome. No such review has
previously been published. Broadly, we found insufficient ev-
idence to conclude that the studied programs were effective in
reducing pregnancy, the primary study outcome. For one of
the three follow-up periods into which results were stratified,
we report a statistically significant increase in pregnancy risk.
We also saw no consistent evidence of increasing condom or
OCP use, or delaying sexual initiation, our secondary out-
comes. However, there were statistically significant decreases
in sexual initiation and lack of condom use for one of the three
follow-up time strata, < 13 months. Because the literature in-
cludes varied study designs, intervention approaches, and
populations, we conducted seven subgroup analyses on vari-
ables that might affect outcomes. None provided consistent
evidence of effectiveness: For pregnancy, the majority of these
subgroup analyses yielded risk reduction ratios which were
not statistically significant. Of those that were statistically sig-
nificant, four were in the direction of decreased risk and two
indicated an increased risk of pregnancy. Regarding the
secondary outcomes, the majority of the pooled risk reduction
ratios were not statistically significant. The six that were sta-
tistically significant for sexual initiation showed a reduced risk
of sexual initiation as did the four for no condom use.
However, the one statistically significant subgroup analysis
for OCP use showed an increased risk of no OCP use.
Our findings are consistent with other systematic reviews
that have examined the effectiveness of programs aimed at
preventing teen pregnancy, finding no statistically significant
effect at preventing pregnancy (Dicenso et al. 2002; Underhill
et al. 2007; Mason-Jones et al. 2016; Scher et al. 2006).
Oringanje et al. (2016) reviewed 53 RCTs from low and
middle-income countries that included school-based and
community-based interventions. They found that interventions
with multiple components (educational and contraceptive pro-
moting) had a significant effect in preventing pregnancy.
Subgroup analysis by educational interventions alone and by
cluster RCTs showed no significant effect in preventing preg-
nancy. None of the four effective interventions were school-
based, the modality of interest for our review. Other reviews
that have found reduced pregnancy risk have relied on studies
of poor quality and included community-based programs (Chin
et al. 2012). Our findings are consistent with those of a com-
panion article in this issue of Prevention Science by
Mirzazadeh et al. which examined the effect of school-based
programs to prevent HIV and other STIs in teens. This review
found no consistent reductions in disease incidence. Since the
risk behaviors for STI transmission and pregnancy are similar,
the findings of the two papers tend to be mutually affirming.
Table 3 Statistically significant pooled relative risk and 95% CI for pregnancy and secondary outcomes
Outcome Number
of IOPTS
RR and 95% CI Stratum Follow-up period
(months)
Increased or
decreased risk
1 Pregnancy 6 1.30 (1.02–1.65) Comprehensive (not abstinence only) 13–23 Increased
2 5 1.39 (1.10–1.75) Single activity type (not package) 13–23 Increased
3 9 0.75 (0.58–0.96) Adult led (not peer led) < 13 Decreased
4 5 0.56 (0.41–0.77) Mixed school and community setting < 13 Decreased
5 5 0.59 (0.39–0.89) Female only (not female + male) < 13 Decreased
6 10 0.73 (0.57–0.64) Sexually experienced + inexperienced < 13 Decreased
7 Sexual initiation 9 0.87 (0.77–0.98) Comprehensive (not abstinence only) < 13 Decreased
8 3 0.93 (0.88–0.98) Observational (not RCT) 13–23 Decreased
9 5 0.81 (0.68–0.97) Observational (not RCT) < 13 Decreased
10 10 0.87 (0.77–0.97) Single activity type (not package) <13 Decreased
11 4 0.80 (0.66–0.98) Female only (not female + male) < 13 Decreased
12 2 0.90 (0.83–0.97) Female + male reported pregnancy 24+ Decreased
13 Condom use 8 0.84 (0.74–0.94) Comprehensive (not abstinence only) < 13 Decreased
14 8 0.83 (0.72–0.96) Single activity type (not package) <13 Decreased
15 6 0.79 (0.62–0.95) Adult led (not peer led) < 13 Decreased
16 8 0.86 (0.75–0.98) Female + male reported pregnancy < 13 Decreased
17 OCP use 2 1.12 (1.02–1.22) Peer led (not adult led) 13–23 Increased
BPooled^results with only one IOPT are excluded
Prev Sci
Our review included abstinence-only interventions
despite earlier reviews suggesting lack of effectiveness
(Chin et al. 2012; Underhill et al. 2007). We did so
because of the importance of this issue, the fact that
their effectiveness remains contested (Weed 2012), and
the possibility that recently published studies could
suggest a different result. Our meta-analysis affirms
earlier findings and did not include new studies on
abstinence-only programs. However, that we also found
no pattern of effectiveness in the comprehensive pro-
grams suggests that reasons for lack of benefit extend
beyond the nature of the curriculum. Unfortunately, the
four pooled RR results that showed statistically signif-
icant reductions in pregnancy, from a total of 30
unique pooled comparisons, are too few to test hypoth-
eses regarding the correlates of program effectiveness.
Similarly, the four individual study (unpooled) IOPTs
that indicated a statistically significant decrease in
pregnancy evinced no particular pattern of intervention
design. All four were comprehensive rather than
abstinence-only and were adult-led. One was imple-
mented in a mixed setting (i.e., school-based program
that included activities in the community or in which
community members visited the school) (Allen et al.
1997), and two were strictly school-based (Allen
et al. 1994; Hawkins et al. 1999)(Appendix D).
Finally, 3 of the 21 studies we evaluated were pub-
lished in 2016, and none of these showed statistically
significant reductions in pregnancy risk. This limited
evidence does not support a hypothesis that recent im-
provements in program design or implementation make
for greater efficacy. Therefore, an important unan-
swered question is, BWhat are the determinants of ef-
fectiveness in school-based pregnancy prevention
programs?^
Some investigators have questioned the premise that teen
pregnancy is a cause of poor health and economic outcomes
(Melissa and Levine 2012; Schalet et al. 2014; Sisson 2012).
They suggest instead that, all else equal, poor life prospects
increase pregnancy risks. If true, it helps explain why the few
hours of a program might not have a marked effect on preg-
nancy rates.
While teen pregnancy prevention programs aim to improve
a range of outcomes, the focus of this study was on pregnancy
and three of pregnancy’s proximate causal predicates. Despite
discouraging findings based on limited data, there may be
specific intervention approaches that are effective. Future re-
search may identify effective behavior change models or may
establish, for example, the efficacy of programs that begin
earlier or extend over many grades. Continued evaluation in-
cluding well-powered, rigorous studies that minimize risk of
bias is needed to identify what types of school-based programs
can reduce adolescent pregnancy rates.
Limitations
Our finding of no consistent pattern of statistically significant
effectiveness in reducing the risk represented by the secondary
outcomes (sexual initiation, no condom, and OCP use) should
be treated with caution. Our review was restricted to studies
that reported on pregnancy and excluded those that measured
secondary outcomes only. We may therefore have analyzed a
biased sample of studies; interventions with studies that report
on pregnancy may be systematically different from those that
do not. Although we believe that the current analysis is com-
prehensive, confidence in substantive conclusions must be
tempered by the poor quality of available evidence. The nature
of school-based programs renders blinding impossible and
true randomization very difficult or impossible. Imprecision
is also inevitable with rare events such as pregnancy, and a
certain amount of contamination and cross-over must be ex-
pected in the context of an uncontrolled setting such as
schools in which students may be transferred or may move
for any number of reasons. Thus, the low quality of evidence
rating should be understood in comparison with more easily
controlled clinical research. Beyond these inherent difficul-
ties, many studies failed to adjust for confounding or had high
loss to follow-up. Thus, it is conceivable that more rigorous
studies might have yielded different and more positive results.
As in all systematic reviews, we only evaluated studies that
met inclusion criteria. Broader criteria, such as acceptance of
earlier studies, might have yielded a different result.
Furthermore, while we made every attempt to search compre-
hensively, it is possible that we missed high-quality studies
which found better effectiveness. Finally, our classification
of programs requires judgments about which informed re-
viewers can disagree. However, while a different classification
of IOPTs would affect a subset of the calculated pooled RRs
and confidence intervals, the basic finding of no consistent
evidence of reduced pregnancy would be unaffected by any
such re-classification.
Conclusion
This review is the first to assess the effectiveness of school-
based interventions in reducing pregnancy in the USA. The
data from included studies provide no consistent evidence that
evaluated programs were effective in reducing pregnancy or in
improving results in the secondary outcomes analyzed. Our
study was not designed to identify specific approaches that
may be effective. There were too few studies of any particular
approach, such as service learning, peer-led interventions, and
approaches based on cognitive behavioral theory and social
learning theory to identify the relative effectiveness of these or
other approaches, nor were we able to assess the relative ef-
fectiveness of programs that begin earlier and may extend
Prev Sci
over many grades, versus those that start later. Continued
evaluation is needed to identify what specific types of
school-based interventions can successfully reduce youth
pregnancy rates.
Funding Information This project was completed with funding from
CAPE (Consortium for Assessment of Prevention Economics), of the
NCHHSTP Epidemiological and Economic Modeling Agreement
(Grant No. U38PS004649), with the Centers for Disease Control and
Prevention. Its contents are solely the responsibility of the authors.
Compliance with Ethical Standards
Conflict of Interest The authors declare that they have no conflict of
interest.
Research Involving Human Participants and/or Animals This article
does not contain any studies with human participants or animals per-
formed by any of the authors.
Informed Consent As no human subjects were involved in the research
undertaken to produce this article, no informed consent was required.
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