Laura Duberstein Lindberg

Explaining Recent Declines in Adolescent Pregnancy in the United States: The Contribution of Abstinence and Improved Contraceptive Use

OBJECTIVES We explored the relative contributions of declining sexual activity and improved contraceptive use to the recent decline in adolescent pregnancy rates in the United States. METHODS We used data from 1995 and 2002 for women 15 to 19 years of age to develop 2 indexes: the contraceptive risk index, summarizing the overall effectiveness of contraceptive use among sexually active adolescents (including nonuse), and the overall pregnancy risk index, calculated according to the contraceptive risk index score and the percentage of individuals reporting sexual activity. RESULTS The contraceptive risk index declined 34% overall and 46% among adolescents aged 15 to 17 years. Improvements in contraceptive use included increases in the use of condoms, birth control pills, withdrawal, and multiple methods and a decline in nonuse. The overall pregnancy risk index declined 38%, with 86% of the decline attributable to improved contraceptive use. Among adolescents aged 15 to 17 years, 77% of the decline in pregnancy risk was attributable to improved contraceptive use. CONCLUSIONS The decline in US adolescent pregnancy rates appears to be following the patterns observed in other developed countries, where improved contraceptive use has been the primary determinant of declining rates.

Adolescent sexual behavior: estimates and trends from four nationally representative surveys.

CONTEXT Accurate information about trends over time in adolescent sexual behavior is essential to understand changes in adolescent pregnancy and sexually transmitted diseases and to monitor the progress of health promotion activities in the United States METHODS Estimates from the National Survey of Family Growth (NSFG), the National Survey of Adolescent Males (NSAM), the Youth Risk Behavior Survey (YRBS) and the National Longitudinal Study of Adolescent Health (Add Health) were compared. While methodologies and populations varied by survey, adolescents aged 15-17 who attend high school were a common subpopulation among all four. For each survey, the prevalence of sexual intercourse, contraceptive use and multiple sexual partners was measured in this population. RESULTS Trend comparisons fell into four categories. First, some similar significant trends were found across surveys. The proportion of all males and of white males who reported ever having had sexual intercourse decreased significantly, while condom use rose significantly among males in both the NSAM and the YRBS. For such behaviors as ever having had sexual intercourse (among Hispanic males and black females), using the pill and using the condom (among all females) and having four or more lifetime sexual partners (among white males), a significant trend was found in one survey while a similar but nonsignificant trend was found in another. Several trend comparisons were not significant in any survey. Finally, having had intercourse in the past three months (among all males and all females), having had two or more partners in the past three months (for males) and having had four or more lifetime sexual partners (among white females and all males) showed a significant trend in one survey but lacked a parallel nonsignificant trend in another. Prevalence estimates in 1995 differed significantly in at least one comparison of surveys for all behaviors except having four or more lifetime sexual partners (both genders) and having two or more recent sexual partners (females). Gender differences within the YRBS and between the NSFG and the NSAM generally were consistent. CONCLUSIONS Trends over time and gender differences were similar across surveys, underscoring their value for tracking adolescent sexual behaviors. Differences in prevalence estimates across surveys probably result from differences in question wording, diverse interview settings and modes of data collection, and varying statistical power. These findings suggest a need to increase our understanding of how methodologies influence survey response in research on adolescents.

Noncoital Sexual Activities Among Adolescents

PURPOSE Although prior research has demonstrated that many adolescents engage in noncoital sexual behavior, extant peer-reviewed studies have not used nationally representative data or multivariate methods to examine these behaviors. We used data from Cycle 6 of National Survey of Family Growth (NSFG) to explore factors related to oral and anal sex among adolescents. METHODS Data come from 2,271 females and males aged 15-19 in 2002. Computer-assisted self-administered interviews were used to collect sensitive information, including whether respondents had ever engaged in vaginal, oral or anal sex. We used t tests and multivariate logistic regression to test for differences and identify independent characteristics associated with experience with oral or anal sex. RESULTS In all, 54% of adolescent females and 55% of adolescent males have ever had oral sex, and one in 10 has ever had anal sex. Both oral sex and anal sex were much more common among adolescents who had initiated vaginal sex as compared with virgins. The initiations of vaginal and oral sex appear to occur closely together; by 6 months after first vaginal intercourse, 82% of adolescents also engaged in oral sex. The strongest predictor of anal sex involvement was time since initiation of vaginal sex and the likelihood of anal sex increased with greater time since first vaginal intercourse. Teens of white ethnicity and higher socioeconomic status were more likely than their peers to have ever had oral or anal sex. CONCLUSIONS Health professionals and sexual health educators should address noncoital sexual behaviors and risk for sexually transmitted infections risk, understanding that noncoital behaviors commonly co-occur with coital behaviors.

Consequences of Sex Education on Teen and Young Adult Sexual Behaviors and Outcomes

PURPOSE This study examined whether formal sex education is associated with sexual health behaviors and outcomes using recent nationally representative survey data. METHODS Data used were from 4,691 male and female individuals aged 15-24 years from the 2006-2008 National Survey of Family Growth. Weighted bivariate and multivariate analyses were conducted by gender, estimating the associations of sex education by type (only abstinence, abstinence and birth control, or neither) before first sexual intercourse, and sexual behaviors and outcomes. RESULTS Receipt of sex education, regardless of type, was associated with delays in first sex for both genders, as compared with receiving no sex education. Respondents receiving instruction about abstinence and birth control were significantly more likely at first sex to use any contraception (odds ratio [OR] = 1.73, females; OR = 1.91, males) or a condom (OR = 1.69, females; OR = 1.90, males), and less likely to have an age-discrepant partner (OR = .67, females; OR = .48, males). Receipt of only abstinence education was not statistically distinguishable in most models from receipt of either both or neither topics. Among female subjects, condom use at first sex was significantly more likely among those receiving instruction in both topics as compared with only abstinence education. The associations between sex education and all longer-term outcomes were mediated by older age at first sex. CONCLUSIONS Sex education about abstinence and birth control was associated with healthier sexual behaviors and outcomes as compared with no instruction. The protective influence of sex education is not limited to if or when to have sex, but extends to issues of contraception, partner selection, and reproductive health outcomes.

Short interpregnancy intervals in the United States.

OBJECTIVE: To investigate the prevalence and correlates of short interpregnancy intervals in the United States. METHODS: We analyzed pregnancy data from a nationally representative sample of 12,279 women from the 2006–2010 National Survey of Family Growth. We limited our sample to second and higher-order births within 5 years of the interview. Interpregnancy intervals were calculated as the interval between the delivery date of the preceding live birth and the conception date of the index pregnancy, with short interpregnancy intervals defined as intervals less than 18 months. We used simple and multivariate logistic regression analyses to examine associations between short interpregnancy intervals and maternal demographic and childbearing characteristics, including pregnancy intention. RESULTS: Among the 2,253 pregnancies in our sample, one third (35%) were conceived within 18 months of a previous birth. After adjusting for sociodemographic and childbearing characteristics, women were significantly more likely to have a short interpregnancy interval if they were aged 15–19 years or married at the time of conception of the index pregnancy, initiated childbearing after age 30 years, or reported the pregnancy as unintended. Short interpregnancy intervals were more likely to be intended among more advantaged women (married, non-Hispanic white, college-educated, or non-Medicaid delivery). We estimate that preventing unintended pregnancies would reduce the proportion of short interpregnancy intervals from 35% to 23%. CONCLUSION: Providing counseling about the potential negative consequences of short interpregnancy intervals and improving womens contraceptive use to reduce rates of unintended pregnancy likely would reduce the proportion of short interpregnancy interval pregnancies in the United States. LEVEL OF EVIDENCE: II

Pregnancy Intentions, Maternal Behaviors, and Infant Health: Investigating Relationships With New Measures and Propensity Score Analysis

The premise that unintended childbearing has significant negative effects on the behavior of mothers and on the health of infants strongly influences public health policy and much of current research on reproductive behaviors. Yet, the evidence base presents mixed findings. Using data from the U.S. National Survey of Family Growth, we employ a measure of pregnancy intentions that incorporates the extent of mistiming, as well as the desire scale developed by Santelli et al. (Studies in Family Planning, 40, 87–100, 2009). Second, we examine variation in the characteristics of mothers within intention status groups. Third, we account for the association of mothers’ background characteristics with their pregnancy intentions and with the outcomes by employing propensity score weighting. We find that weighting eliminated statistical significance of many observed associations of intention status with maternal behaviors and birth outcomes, but not all. Mistimed and unwanted births were still less likely to be recognized early in pregnancy than intended ones. Fewer unwanted births received early prenatal care or were breast-fed, and unwanted births were also more likely than intended births to be of low birth weight. Relative to births at the highest level of the desire scale, all other births were significantly less likely to be recognized early in pregnancy and to receive early prenatal care.

Changing behavioral risk for pregnancy among high school students in the United States, 1991-2007.

PURPOSE After dramatic declines in teen births and pregnancies from 1991 to 2005, teen birth rates in the United States increased in 2006 and 2007. We examined behavioral determinants of these trends and the likely direction of future trends. METHODS Pregnancy risk was estimated based on recent sexual activity, method of contraception used, and method-specific contraceptive efficacy, using data from young women on the national Youth Risk Behavior Survey (N approximately 125,000). Weighted logistic and linear regression were used to test for linear and quadratic (curved) trends over time. RESULTS Between 1991 and 2007, behavioral risk for pregnancy declined, with all of the decline occurring between 1991 and 2003. Improvements in contraceptive use from 1991 to 2003 were found in condom use, nonuse, and use of withdrawal. Recent sexual activity (past 3 months) was unchanged over the entire period, except among black students. Quadratic changes were found in pregnancy risk for black teens and in condom use among all teens and black teens, suggesting that trends had reversed or flattened out. Although no change was found for any behavior between 2003 and 2007, pregnancy risk among sexually active teens demonstrated a borderline increase (p=.06) and small nonsignificant declines were seen for specific contraceptive methods. Pregnancy risk estimated from behavioral data correlated well with actual changes in teen pregnancy rates (1991-2004) and birth rates (1991-2006). DISCUSSION After improvement in the 1990s and early 2000s, trends in behavioral risk for pregnancy appear to have stalled or even reversed among certain groups since 2003. These behavioral trends are consistent with the 2006 and 2007 increases in the teen birth rate. They may well portend further increases in 2008.

Understanding the Decline in Adolescent Fertility in the United States, 2007–2012

Purpose The decline in U.S. adolescent fertility has accelerated since 2007. Modeling fertility change using behavioral data can inform adolescent pregnancy prevention efforts. Methods We used data on sexual activity and contraceptive use from National Surveys of Family Growth for young women 15–19 years of age, and contraceptive failure rates, to estimate a Pregnancy Risk Index (PRI) for the periods 2007, 2009, and 2012. Logistic regression was used to test for change over time in sexual activity, contraceptive use, and PRI. Statistical decomposition was used to calculate attribution of change in the PRI to changes in sexual activity or contraceptive method use. Results Sexual activity in the last 3 months did not change significantly from 2007 to 2012. Pregnancy risk declined among sexually active adolescent women (p = .046), with significant increases in the use of any method (78%–86%, p = .046) and multiple methods (26%–37%, p = .046). Use of highly effective methods increased significantly from 2007 to 2009 (38%–51%, p = .010). Overall, the PRI declined at an annual rate of 5.6% (p = .071) from 2007 to 2012 and correlated with birth and pregnancy rate declines. Decomposition estimated that this decline was entirely attributable to improvements in contraceptive use. Conclusions Improvements in contraceptive use appear to be the primary proximal determinants of declines in adolescent pregnancy and birth rates in the United States from 2007 to 2012. Efforts to further improve access to and use of contraception among adolescents are necessary to ensure they have the means to prevent pregnancy.

Young men's experience with condom breakage.

In a nationally representative sample of men aged 17-22, 23% of those using condoms reported experiencing at least one condom break during the previous 12 months. Of all condoms used, 2.5% had broken. In multivariate analyses, increased experience with condoms reduced the likelihood of experiencing condom breakage. Recent sex education was associated with an almost 80% decrease in the risk of breakage among young men who used condoms infrequently. Young males who had ever had a sexually transmitted disease (STD), or whose sexual partner had had an STD, were almost three times as likely as other respondents to have experienced condom breakage. In addition, young men with a household income of less than

Older, but Not Wiser: How Men Get Information about AIDS and Sexually Transmitted Diseases after High School:

60,000 were 2-3 times as likely to have broken a condom as were those with a higher household income.