Correlates of age at first sexual intercourse in a national sample of young women

Phenols, Parabens, Phthalates and Puberty: a Systematic Review of Synthetic Chemicals Commonly Found in Personal Care Products and Girls' Pubertal Development

PURPOSE OF REVIEW

Exposure to endocrine disrupting chemicals through personal care products (PCPs) is widespread and may disrupt hormone-sensitive endpoints, such as timing of puberty. Given the well-documented (and ongoing) decline in age at menarche in many populations, we conducted a systematic review of the epidemiological literature on exposure to chemicals commonly found in PCPs (including certain phthalates, phenols, and parabens) in relation to girls' pubertal development.

RECENT FINDINGS

The preponderance of research on this topic has examined phthalate exposures with the strongest evidence indicating that prenatal monoethyl phthalate (MEP) concentrations may be associated with slightly earlier timing of puberty, including age at menarche. Findings examining peri-pubertal phthalate exposures and pubertal outcomes were less consistent as were studies of prenatal and peri-pubertal phenol exposures. Very few studies had examined parabens in relation to girls' pubertal development. Common study limitations included potential exposure misclassification related to use of spot samples and/or mistimed biomarker assessment with respect to the outcomes. The role of body size as a mediator in these relationships remains unresolved. Overall, evidence of associations between chemical exposures in PCPs and girls' pubertal development was conflicting. When associations were observed, effect sizes were small. Nevertheless, given the many environmental, social, and behavioral factors in the modern environment that may act synergistically to accelerate timing of puberty, even marginal changes may be cause for concern, with implications for cancer risk, mental health, and cardiometabolic disease in later life.

Relationship Foraging: Does time spent searching predict relationship length?

Animals foraging for resources often need to alternate between searching for and benefiting from patches of those resources. Here we explore whether such patterns of behavior can usefully be applied to the human search for romantic relationships. Optimal foraging theory suggests that foragers should alter their time spent in patches based on how long they typically spend searching between patches. We test whether human relationship search can be described as a foraging task that fits this OFT prediction. By analyzing a large, demographically representative dataset on marriage and cohabitation timing using survival analysis, we find that the likelihood of a relationship ending per unit time goes down with increased duration of search before that relationship, in accord with the foraging prediction. We consider the possible applications and limits of a foraging perspective on mate search and suggest further directions for study.

Trends in Sexual Behaviour in Czech Schoolchildren between 2002-2014

OBJECTIVE

The aim of this study was to report on trends in the prevalence in age at first intercourse of Czech schoolchildren and a difference between sexes.

METHODS

Prevalence in age at first intercourse of Czech schoolchildren was observed under the Health Behaviour in School-aged Children study in the years 2002, 2006, 2010 and 2014. In addition, a random representative sample of children attending 9th grade completed the questions related to sexual behaviour. A total of 4,804 boys and girls at the age of 15 years were included in the study. The chi-square test and analysis of variance were used for data assessment.

RESULTS

Experience with first sexual intercourse before 15 years was confirmed by 16% of boys and 19.4% of girls. Average age of coitarche in both sexes most often ranged between 14 and 15 years. Since 2006 boys had significantly lower age at coitarche. Only in 2010 the girls had first intercourse more frequently than boys. Since 2010 the number of Czech adolescents of both sexes having first intercourse before the age of 15 years has significantly increased. However, a rise in average age of coitarche over 15 years in both sexes occurred in 2014.

CONCLUSIONS

The number of Czech children having a sexual intercourse before 15 years has significantly increased since 2010.

Adolescents' Perceived Ability to Say "No" to Unwanted Sex

Although violent sexual assaults occur in adolescence, lessfrequently recognized are the more subtle forms of sexual coercion. This investigation focused on adolescents'perceived ability to say no to pressures from a partner to engage in unwanted sex. With a sample of 2,472 10th-grade White, Hispanic, and Black adolescents, which adolescents may have had a more difficult time saying no to unwanted sex was examined. Results indicated that females were more likely than males to believe that they could say no to unwanted sex, but no consistent differences were found among the racial and ethnic groups. Multivariate analyses revealed several other predictors of the perceived ability to say no, including a less-permissive attitude toward sex, the low importance of peer influence and, for females, a generalized sense of self-efficacy. Implications of these results for intervention andfuture research are discussed.

Genetic and Environmental Contributions to Variance in Age at First Sexual Intercourse

Little is known about the relative importance of genetic and environmental factors as determinants of age at first sexual intercourse In this study, subjects were 5,080 individuals from the Australian Twin Registry (3,310 females, I 770 males, age range 27-70 years, median 40 years) who completed a semistructured interview by telephone in 1992-1993 Self-reported age at first intercourse correlated higher for identical (monozygotic) twins than for nonidentical (dizygotic) twins Structural equation model fitting found that the genetic contribution to variance was considerably greater among twins aged 40 years or less (72% for males and 49% for females) than for those aged from 41 to 70 years (0% for males and 32% for females) Among the older cohort, there was evidence that somewhat different aspects of the shared social environment influenced age at onset in males and females In a more laissez-faire social climate in recent decades, it is likely that biological and psychological characteristics that are partly under genetic control significantly influence the age at which a person commences sexual activity

Father absence and age at menarche : A test of four evolutionary models

Life history data, attractiveness ratings of male photographs, and attitudes towards partnership and child-rearing of 321 women were used to test four evolutionary models (quantitative reproductive strategy, male short-age, polygyny indication, and maternal reproductive interests) which attempt to explain the influence of family composition on reproductive strategies. Links between early menarche and other markers of reproductive strategy were investigated. Childhood stress and absence of a father figure, whether genetically related or not, were found to have accelerated menarche whereas having younger siblings decelerated it. Early menarche was associated with attractiveness ratings, the number of partners desired for the immediate future, and the early onset of intimate relationships. It was not linked with sociosexual orientation, mate choice criteria, and investment in the subjects' own children, but these three markers were interrelated. The implications of the findings for the four evolutionary models are discussed.

The Role of Religiousness and Gender in Sexuality Among Mexican Adolescents

This study examined the role of religiousness and gender in age at first intercourse, and sexual expectations and values in Mexico, a macrocontext where the majority is Mexican and Catholic (83%). Participants were Catholic and nonreligious adolescents (54% girls) attending middle (71%) or high school. Findings indicated that Catholic adolescents engaged in sexual intercourse at later ages than nonreligious adolescents. Both religious attendance and importance of religion and values in sexual decision making were associated with more conservative sexual values. Boys who were raised Catholic were more likely to endorse female virginity values and were less likely to expect to wait to have sex until married than nonreligious boys. These associations were not significant among girls. Catholic boys may be more likely to internalize sexual double standard beliefs regarding premarital sex than nonreligious boys. This study expands our understanding of the role of religiousness in Mexican adolescents' sexuality.

Age at menarche and age at first sexual intercourse: a prospective cohort study

OBJECTIVE

Younger age at menarche (AAM) may put girls at risk for earlier first sexual intercourse (FSI). Young age at FSI has far-reaching negative outcomes. We describe the longitudinal relationship between AAM and FSI in a large prospective birth cohort.

METHODS

AAM was collected from 554 girls from the Western Australia (Raine) Pregnancy Cohort Study, prospectively from age 10 or retrospectively at age 14. Age at FSI was collected at ages 17 and 20. Cox regression models describe likelihood of FSI by age and years since menarche for younger (<12 years) and older (≥14 years) AAM relative to average AAM (12-13 years).

RESULTS

Girls with younger AAM and average AAM were equally likely to have FSI by age 16 (adjusted hazard ratio [aHR]: 0.90 [95% confidence interval (CI): 0.60-1.35]). FSI by age 16 was less likely among girls with older AAM than those with average AAM (aHR: 0.35 [95% CI: 0.17-0.72]). Girls with younger AAM had a longer median interval between menarche and FSI than girls with average AAM (5.0 years [interquartile range: 4.4-8.5 years] vs 3.7 years [interquartile range: 2.4-5.3 years]). Those with younger AAM were less likely to report FSI within 4 years of menarche than those with average AAM (0-2 years aHR: 0.04 [95% CI: 0.01-0.31]; 2-4 years aHR: 0.36 [95% CI: 0.23-0.55]). By age 20, 429 girls (77.4%) reported FSI.

CONCLUSIONS

Younger AAM was not a risk factor for younger age at FSI in this cohort.

Increasing the prevalence of successful children: The case for community intervention research

This paper makes a case for research on community interventions on child rearing. Sufficient evidence has accumulated about the development of children's problem behavior to justify evaluating efforts to reduce the prevalence of these problems in whole communities. The contextual risk factors for diverse child behavior problems are well understood, and interventions to ameliorate individual risk factors have been developed and evaluated. Because interventions with individual children have proven to be efficacious, it is now appropriate to direct energy toward reducing the prevalence of children with behavior problems. At the same time, existing interventions have limitations. Community interventions may be needed to modify the larger social context for families. This paper enumerates possible components of a community intervention to improve child-rearing outcomes. Existing evidence indicates that communities would benefit from making parent training and family support programs available to parents. Validated methods of identifying and remediating academic and behavioral problems in schools are available, but influencing schools to adopt them remains a problem. Community organizing could mobilize communities to allocate the resources necessary to support such parenting and schooling programs as well as encourage their adoption. Media campaigns could foster community support and directly influence parenting practices. Efforts to modify peer influences to use illicit substances have received empirical support; similar efforts may be relevant to preventing other problems. The development of a science of community interventions on child rearing is hampered by overreliance on randomized control trials. For this reason, two examples of time-series experimental evaluations of community intervention components are described here.

Concurrent multiple health risk behaviors among adolescents in Luangnamtha province, Lao PDR

Background

Multiple health risk behaviors (HRBs) among adolescents pose a threat to their health, including HIV/AIDS. Health risk behaviors such as alcohol use, smoking, substance use, and sexual risk behaviors among youth have been shown to co-occur with each others. The objectives of this study was to estimate the prevalence of single and concurrent health risk behaviors and to explore how health risk behavior is associated with socio-demographic factors and peers' behaviors.

Methods

A cross sectional design was used to examine health risk behaviors of adolescents between the age 14 and 19 years living in the Luangnamtha province, Lao PDR. The study was conducted between June and August, 2008. An ordinal logistic regression model that simultaneously explored demographic factors and the influence of the behavior of peers on three categories of multiple HRBs (no risk, one risk, and two or more health risk behaviors) was performed.

Results

A total of 1360 respondents, 669 (49.1%) boys with mean age 16.7 ± 1.6 and 699 (50.9%) girls aged 16.1 ± 1.5 were recruited into the study. The majority reported two or fewer risk behaviors. However, multiple risk behaviors increased with age for both sexes. About 46.8% (n = 637) reported no risk, 39.3 percent (n = 535) reported one risk, 8.1 percent (n = 110) reported two risks, and 5.8 percent reported more than two health risk behaviors.

The protective factors among boys were school attendance (OR = .53, CI = .33-.86), being Hmong and Yao ethnicity (OR = .48, CI-.26-.90), while being above the age of 15 (OR = 2.20, 95% CI = 1.33-3.60), Akha ethnicity (OR = 2.20, 95% CI = 1.04-4.61), peer's smoking (OR = 3.11, 95% CI = 2.1-4.6), and peer's drinking alcohol (OR = 1.88, 95% CI = 1.1-3.21) were significantly associated with the presence of multiple risk behaviors among boys.

Having some education (OR = 0.17, 95% CI = 0.06-0.45), and being of Hmong and Yao ethnicity (OR = 0.38, 95% CI = 0.18-0.80) were factors that protected girls from multiple risk behaviors; while peer's drinking alcohol (OR = 2.55, 95% CI = 1.59-4.09) and peer's being sexually active (OR = 2.82, 95% CI = 1.65-4.8) were significantly associated with the presence of multiple risk behaviors among girls.

Conclusion

There are sex, age and ethnic differences in the concurrent health risk behaviors. The influencing factors are adolescent's education and peer influence. Interventions should focus to encourage adolescents to complete the compulsory primary education as well as help them to establish friendships and follow peers with good behavior. Risk reduction messages need to take account of diverse multiple HRBs within the specific socio-cultural and gender specific context and target vulnerable adolescents such as ethnic minorities and less educated adolescents.

Timing of sexual maturation and women's evaluation of men

Many antecedents and consequences of an accelerated sexual maturation are associated with negative experiences with the opposite sex. Here we show a connection between menarcheal age, a salient sign of female sexual maturation, and the implicit attitude toward men in later adulthood. In Study 1, earlier age at first menstruation was associated with automatic negative evaluations of male faces but not female ones. Study 2 revealed a relationship between early age of menarche and an implicit association between the concepts male and danger. In Study 3, the earlier the menarche, the larger was the estimated egocentric distance of virtual male voices and the shorter the estimated distance of female voices. These results, obtained about a decade after onset of menstruation, suggest that apparently subtle differences in the onset of sexual maturation may have long-lasting implications for intersexual relationships.

Character as a predictor of reproductive health outcomes for youth: a systematic review

To review research examining the influence of character on adolescent sexual and reproductive health (ASRH). We defined character as comprising two positive youth development constructs: prosocial norms and spirituality. We conducted a systematic review of behavioral research published from 1985 through 2007 that examined the association between two character constructs (prosocial norms and spirituality) and ASRH outcomes. We coded results as showing a protective association, risk association, or no association, and as longitudinal, or cross-sectional. We considered consistent associations from at least two longitudinal studies for a given outcome to be sufficient evidence for a protective or risk association. There is sufficient evidence to indicate that prosocial norms and spirituality can be protective factors for some ASRH outcomes including intention to have sex, early sex or ever having sex, contraceptive and condom use, frequency of sex, and pregnancy. The generalizability of findings by age, race/ethnicity, and gender was unclear. Findings suggest that some character sub-constructs are associated with a reduced likelihood of several adverse ASRH outcomes and with an increased likelihood of using contraceptives and intending to use condoms. Further research is needed to better understand mixed results and results showing some character sub-constructs, such as religious affiliation, to be associated with adverse ASRH outcomes.

Maternal programming of sexual behavior and hypothalamic-pituitary-gonadal function in the female rat

Variations in parental care predict the age of puberty, sexual activity in adolescence and the age at first pregnancy in humans. These findings parallel descriptions of maternal effects on phenotypic variation in reproductive function in other species. Despite the prevalence of such reports, little is known about potential biological mechanisms and this especially true for effects on female reproductive development. We examined the hypothesis that parental care might alter hypothalamic-pituitary-ovarian function and thus reproductive function in the female offspring of rat mothers that vary pup licking/grooming (LG) over the first week postpartum. As adults, the female offspring of Low LG mothers showed 1) increased sexual receptivity; 2) increased plasma levels of luteinizing hormone (LH) and progesterone at proestrus; 3) an increased positive-feedback effect of estradiol on both plasma LH levels and gonadotropin releasing-hormone (GnRH) expression in the medial preoptic region; and 4) increased estrogen receptor α (ERα) expression in the anterioventral paraventricular nucleus, a system that regulates GnRH. The results of a cross-fostering study provide evidence for a direct effect of postnatal maternal care as well as a possible prenatal influence. Indeed, we found evidence for increased fetal testosterone levels at embryonic day 20 in the female fetuses of High compared to Low LG mothers. Finally, the female offspring of Low LG mothers showed accelerated puberty compared to those of High LG mothers. These data suggest maternal effects in the rat on the development of neuroendocrine systems that regulate female sexual behaviour. Together with studies revealing a maternal effect on the maternal behavior of the female offspring, these findings suggest that maternal care can program alternative reproductive phenotypes in the rat through regionally-specific effects on ERα expression.

Environmental Programming of Phenotypic Diversity in Female Reproductive Strategies

Among invertebrates, certain hermaphroditic species reproduce sexually, but with no process of sexual differentiation. In such cases the brain is bisexual: Each member of the species develops male and female sexual organs and retains the capacity to express both male and female patterns of reproductive behavior. Members of such species can reproduce socially or alone. Mammals and many other species reproduce both sexually and socially, which requires an active process of sexual differentiation of reproductive organs and brain. The primary theme of this chapter is simply that this process admits to variation and thus individual differences in gender-specific patterns of reproductive function. The focus on this chapter is the often neglected variation in the development of reproductive function in the female mammal. The basic premise is that evolution has not defined any single, optimal reproductive phenotype, but rather encourages plasticity in specific reproductive traits among same sex members of the species that are derived from variations in the quality of the prevailing environment during development that are mediated by alterations in parent-offspring interactions. Thus, the variations in parental care that define the reproductive phenotype of the offspring are influenced by the quality of the environment (i.e., nutrient availability, predation, infection, population density, and so on).

Cycles of shame: menstrual shame, body shame, and sexual decision-making

Although numerous factors have been implicated in women's sexual decision-making, less attention has been focused on how their feelings about their bodies and reproductive functions affect these processes. Recent findings link menstrual shame to lower levels of sexual activity and higher levels of sexual risk; however the mechanisms behind these relations remain unexplored. Accordingly, this study investigates the contributions of menstrual shame and global body shame to sexual decision-making among 199 undergraduate women. Using structural equation modeling, we evaluated a mediated model, whereby menstrual shame is indirectly associated with sexual decision-making via body shame. As expected, women who reported feeling more comfort about menstruation also reported more body comfort and, in turn, more sexual assertiveness, more sexual experience, and less sexual risk.

Timing of puberty and sexuality in men and women

We examined the relations among timing of puberty, timing of first experience of sexual arousal, strength of sex drive, and sexual attitudes and behaviors in 277 men (M age, 22.4 years) and women (M age, 21.8 years). Kinsey had suggested that earlier maturers have a stronger sex drive and, therefore, engage in a higher frequency of sexual behaviors (including same-sex contacts) than do later maturers. The purpose of this study was to test Kinsey's claim. Participants completed questionnaires on pubertal timing, timing of first experience of sexual arousal, sex drive in adulthood, sexual attitudes (e.g., sociosexuality or degree of comfort with casual sex), and sexual behaviors (e.g., lifetime number of sexual partners). Timing of puberty (i.e., emergence of secondary sex characteristics) was related to these variables for men but not for women. Timing of first sexual arousal was related to several aspects of adult sexuality in both sexes, but particularly in women. Earlier first sexual arousal was associated with having a higher sex drive, a less restricted sociosexual orientation, and with having had more sexual partners than was later first sexual arousal. Earlier first sexual arousal, but not timing of puberty, was related to sexual orientation for women only. We discuss classes of explanations for these results.

Timing of pubertal maturation in girls: an integrated life history approach

Life history theory provides a metatheoretical framework for the study of pubertal timing from an evolutionary-developmental perspective. The current article reviews 5 middle-level theories--energetics theory, stress-suppression theory, psychosocial acceleration theory, paternal investment theory, and child development theory--each of which applies the basic assumptions of life history theory to the question of environmental influences on timing of puberty in girls. These theories converge in their conceptualization of pubertal timing as responsive to ecological conditions but diverge in their conceptualization of (a) the nature, extent, and direction of environmental influences and (b) the effects of pubertal timing on other reproductive variables. Competing hypotheses derived from the 5 perspectives are evaluated. An extension of W. T. Boyce and B. J. Ellis's (in press) theory of stress reactivity is proposed to account for both inhibiting and accelerating effects of psychosocial stress on timing of pubertal development. This review highlights the multiplicity of (often unrecognized) perspectives guiding research, raises challenges to virtually all of these, and presents an alternative framework in an effort to move research forward in this arena of multidisciplinary inquiry.

Building teen power for sexual health

Alarming numbers of teens engage in behaviors that place them at risk for pregnancy and sexually transmitted infections (STIs) including AIDS. Intervention studies targeted toward reducing risky sexual behavior and improving school retention and literature about variables that affect risky sexual behavior and school performance were reviewed to develop the Social-Cognitive Model for Sexual Behavior During Adolescence. Interventions that target change in the family and school environments in addition to building the personal capacities of each teen have the potential to be effective. Many environmental factors cannot be altered, but the intervention can help reframe the situation and provide the knowledge, specific skills, role models, and rehearsal that promote change. The 13-week school-based intervention assists students identify how personal strengths and family, school, and neighborhood environmental factors can reinforce health behaviors and choices.

Sexual initiation: predictors and developmental trends

BACKGROUND

Early initiation of sexual intercourse is associated with increased risk for acquiring sexually transmitted diseases.

GOAL

To examine variables related to sexual initiation and developmental changes in the reasons why adolescent girls have sexual intercourse.

STUDY DESIGN

A longitudinal study of girls recruited from an adolescent medicine clinic was performed.

RESULTS

Logistic regression showed that girls who described their families as being expressive, having a moral-religious emphasis, providing supervision, and having greater maternal education, and who experienced menarche at an older age were older at sexual initiation. On the basis of contingency analyses, younger girls were less likely to report attraction or love, and more likely to report peers having sex as a reason for sexual intercourse at initiation. A generalized estimating equation analysis indicated that girls at younger ages are more likely to report curiosity, a grown-up feeling, partner pressure, and friends having sexual intercourse as reasons for intercourse. Girls at older ages are more likely to report a feeling of being in love, physical attraction, too excited to stop, drunk or high partner, and feeling romantic as reasons for having sexual intercourse.

CONCLUSIONS

Prevention programs should include a focus on familial characteristics and susceptibility to peer norms. They should be conducted with sensitivity to the developmental changes in intimate relationships that occur during adolescence.

Cultural, contextual, and intrapersonal predictors of risky sexual attitudes among urban African American girls in early adolescence

The role of cultural factors in explaining sexual attitudes among African American urban girls, aged 10-13 years, was investigated in this study. The authors predicted that girls with higher school interest, family cohesion, religiosity, and behavioral self-esteem would endorse less risky sexual attitudes. Also, older girls were expected to have more risky sexual attitudes than younger girls, and girls from 1- rather than 2-parent households were expected to have more risky sexual attitudes. The authors hypothesized that ethnic identity and gender role orientations would contribute to explaining variability in sexual attitudes after controlling for contextual and intrapersonal variables. A questionnaire containing measures of the study constructs was administered to 214 girls who were participants in a substance abuse prevention program. Pretest data were used in analyses. A final regression model accounted for 23% of the variance in sexual attitudes. Age and behavioral self-esteem were significant predictors, with younger teens and teens with higher behavioral self-esteem having less risky sexual attitudes. Cultural variables contributed to explaining variation in sexual attitudes after other variables were controlled for. Higher levels of ethnic identity were associated with less risky sexual attitudes. A masculine gender role orientation was associated with more risky sexual attitudes.

Ecological factors associated with adolescent sexual activity

Bronfenbrenner's (1979) ecological systems theory was used as an organizing framework for the research on teenage sexual activity. Per Bronfenbrenner's theory, the literature is discussed according to macrolevel (system-wide), mesolevel (immediate social environment), and microlevel (individual) factors that are associated with adolescent sexual involvement. Following the review, implications for social work are explored.

Quality of early family relationships and individual differences in the timing of pubertal maturation in girls: a longitudinal test of an evolutionary model

In an 8-year prospective study of 173 girls and their families, the authors tested predictions from J. Belsky, L. Steinberg, and P. Draper's (1991) evolutionary model of individual differences in pubertal timing. This model suggests that more negative-coercive (or less positive-harmonious) family relationships in early childhood provoke earlier reproductive development in adolescence. Consistent with the model, fathers' presence in the home, more time spent by fathers in child care, greater supportiveness in the parental dyad, more father-daughter affection, and more mother-daughter affection, as assessed prior to kindergarten, each predicted later pubertal timing by daughters in 7th grade. The positive dimension of family relationships, rather than the negative dimension, accounted for these relations. In total, the quality of fathers' investment in the family emerged as the most important feature of the proximal family environment relative to daughters' pubertal timing.

Does child abuse predict adolescent pregnancy?

OBJECTIVE

To determine whether sexual and nonsexual childhood abuse are risk factors for early adolescent sexual activity and pregnancy. DESIGN; Cross-sectional study.

SETTING

Prenatal clinic within an inner-city teaching hospital from June 1990 to August 1991.

POPULATION

One thousand twenty-six primiparous, African-American women enrolled in a randomized clinical trial of nurse home visitation.

MAIN OUTCOME MEASURES

Four measures of child abuse were used: sexual abuse, incidents of physical abuse, any major physical abuse, and emotional abuse. The outcome measures were age of first consensual coitus and age of first pregnancy.

RESULTS

After adjustments for household income, parental separation, urban residence, age of menarche, and teen smoking, sexual abuse during childhood was associated with younger age at first coitus (7.2 months; 95% confidence interval [CI], 2.6 to 11.7 months) and younger age at first pregnancy (9.7 months; 95% CI, 3.0 to 16.3 months). Incidents of physical abuse showed minimal effect on age at first coitus (1.2 days per incident; 95% CI, 0.5 to 1.9 days) and no effect on age of first pregnancy. A history of major physical abuse or emotional abuse showed no effect on age of first coitus or first pregnancy.

CONCLUSION

Child sexual abuse, but not child physical or emotional abuse, seems to be a risk factor for earlier pregnancy among African-American adolescents.

Female adolescents and onset of sexual intercourse: a theory-based review of research from 1984 to 1994

PURPOSE

To review a decade of research on the correlates of early onset of sexual intercourse among female adolescents in the United States, using Social Cognitive Theory as a framework for classification.

METHODS

Forty-nine studies published in peer-reviewed journals between 1984 and 1994 were reviewed and their findings coded by two independent coders.

RESULTS

Findings indicate that most of the studies emphasized quantitative methodologies, using cross-sectional designs and univariate statistical analyses. Many studies lacked a theoretical framework or conceptual model to guide their investigations. When evaluating empirical findings, 61% of the studies found environmental correlates and 47% found biological factors (e.g., age and pubertal development) to be significantly associated with early initiation of sexual intercourse.

CONCLUSION

These findings raise important questions about the quality of research on adolescent sexuality, as well as its relationship to the development of risk-reduction programs which tend to focus mainly on intrapersonal factors (such as attitudes, knowledge, and expectancies.

The influence of puberty, family processes, and leisure activities on the timing of first sexual experience

This study investigated the effects of pubertal timing, demographics, family processes, and leisure activities on the timing of first sexual experience. The sample included 15-18-year-old adolescents from the former East and West Germanys. Hierarchical model using Cox regression examined the differences in the patterns of predictors by nation and sex. Higher levels of parental monitoring predicted later initiation of sexual experience for West males and females and East males. In the final model pubertal timing was significant only for East males. Higher levels of risky leisure predicted earlier first sexual experience for East males and females and West females. Social-romantic leisure was a significant predictor of earlier timing for both West males and females.

Teenage sexual attitudes in China

Not much is known about the sexual attitudes of Chinese teenagers. In this article we endeavor to address this void by examining the sexual attitudes of Chinese teenagers with survey data collected in Sichuan Province in 1988. Our analysis has two goals: first, to describe aggregate attitudes toward premarital sexual practices; and second, to identify the principal factors that influence these attitudes. To accomplish the second goal we estimate several regression equations with predictor variables known to influence teen sexual attitudes. Our analysis reveals major differences and similarities between China and the United States and indicates that China's teenagers are somewhat strongly opposed to teen sexual contact, but seem to be more understanding of others who so engage, despite strike laws and public morality forbidding it.

A social contagion model of adolescent sexual behavior: explaining race differences

Black adolescents in the United States consistently report an earlier age of first intercourse than White adolescents. Purely psychosocial explanations of this finding have been less than successful. We propose an "epidemic" model that combines social contagion (a psychosocial process) and pubertal maturation (a biological process). This epidemic model permits social contacts among adolescents of the same age and also among younger and older adolescents. The model statistically fit the actual growth curve of sexuality well for Whites; its fit was not as good for Blacks. From computer simulation analyses, we concluded that pubertal maturation may be more important in accounting for the racial difference in the onset of sexual intercourse than previously thought.