Coerced first sexual intercourse and selected reproductive health outcomes among young women in KwaZulu-Natal, South Africa

Coercion may play an important role in compelling young women to engage in sexual intercourse at an early age. With a decline in age at first intercourse and increased reporting of coercive first sex, concerns of adverse reproductive health outcomes such as unintended pregnancy and sexually transmitted infections (STIs), including HIV, have become important issues, particularly in the context of a high HIV prevalence. This paper uses data collected in 2001 from the second round of a longitudinal study of 1130 sexually experienced young women in KwaZulu-Natal to investigate the relationship between coerced first intercourse and selected reproductive health outcomes and behaviours. Nearly 46% of all sexually experienced young women had reported that their first sexual encounter had been coerced. Young women who reported being coerced at first sex were significantly more likely to be Black and living in an urban area. Those who had been coerced at first sex were also more likely to report having had an STI and having experienced unintended pregnancy, than those who had not been coerced at first sex. Coercion at first sex is an important social and public health problem that has a serious impact on the reproductive health and behaviours of young women. Interventions should directly address the issue of sexual coercion by ensuring young women are aware of their reproductive rights.     

Early stress predicts age at menarche and first birth,adult attachment,and expected lifespan

Life history theory suggests that in risky and uncertain environments the optimal reproductive strategy is to reproduce early in order to maximize the probability of leaving any descendants at all. The fact that early menarche facilitates early reproduction provides an adaptationist rationale for our first two hypotheses: that women who experience more risky and uncertain environments early in life would have (1) earlier menarche and (2) earlier first births than women who experience less stress at an early age. Attachment theory and research provide the rationale for our second two hypotheses: that the subjective early experience of risky and uncertain environments (insecurity) is (3) part of an evolved mechanism for entraining alternative reproductive strategies contingent on environmental risk and uncertainty and (4) reflected in expected lifespan. Evidence from our pilot study of 100 women attending antenatal clinics at a large metropolitan hospital is consistent with all four hypotheses: Women reporting more troubled family relations early in life had earlier menarche, earlier first birth, were more likely to identify with insecure adult attachment styles, and expected shorter lifespans. Multivariate analyses show that early stress directly affected age at menarche and first birth, affected adult attachment in interaction with expected lifespan, but had no effect on expected lifespan, where its original effect was taken over by interactions between age at menarche and adult attachment as well as age at first birth and adult attachment. We discuss our results in terms of the need to combine evolutionary and developmental perspectives and the relation between early stress in general and father absence in particular. This work was supported by The University of Melbourne Department of Obstetrics and Gynaecology. James S. Chisholm is Professor in the School of Anatomy and Human Biology at the University of Western Australia. He is an anthropologist whose interests lie in the fields of human behavioral biology, evolutionary ecology, life history theory, and parental investment theory, where he focuses on infant social-emotional development, the development of reproductive strategies, and the integration of evolutionary, developmental, and cultural psychology and public health. Julie A. Quinlivan is Associate Professor in Obstetrics and Gynaecology at the University of Melbourne and Head of the Maternity Care Program at the Royal Women’s Hospital, Melbourne. Her interests are teenage pregnancy, domestic violence, child abuse prevention, and high-risk pregnancy. Rodney W. Petersen is Senior Lecturer in Obstetrics and Gynaecology at the University of Melbourne and Senior Consultant in Obstetrics and Gynaecology at the Royal Women’s Hospital and Sunshine Hospital in Melbourne. His interests are in psychosocial aspects of women’s health and cancer. David A. Coall is a Ph.D. student in the School of Anatomy and Human Biology at the University of Western Australia. His main interest lies in the application of evolutionary theory within an epidemiological framework. He is currently working on the synthesis of life history theory, parental investment theory, and parent-offspring conflict theory in exploring factors that influence variation in human birth weight and placental weight.     

Age at menarche,socio‐sexual behavior,and fertility

Abstract

This paper examines the relationship between age at menarche and fertility from two perspectives. Age at menarche is regarded as a crude indicator of the timing of fecundity that may affect the timing of conception among those sexually active; and age at menarche is regarded as a crude indicator of the timing of sexual maturation that may influence the timing of socio‐sexual behavior, namely dating and sexual intercourse. The data are drawn from a survey of New York City women who recently had their first child. The findings suggest that age at menarche as an indicator of fecundity is not a good predictor of the timing of the first birth, when controlling for age at first sexual intercourse. Looking only at initial noncontraceptors, however, we find the relationship is stronger. Age at menarche, viewed as an indicator of the timing of sexual maturation, does seem to have some influence on the timing of dating, but only for Blacks. For both races, age at first date is related to age at first sexual intercourse.     

Father absence, parental care, and female reproductive development

This study examines female reproductive development from an evolutionary life history perspective. Retrospective data are for 10,847 U.S. women. Results indicate that timing of parental separation is associated with reproductive development and is not confounded with socioeconomic variables or phenotypic correlations with mothers' reproductive behavior. Divorce/separation between birth and 5 years predicted early menarche, first sexual intercourse, first pregnancy, and shorter duration of first marriage. Separation in adolescence was the strongest predictor of number of sex partners. Multiple changes in childhood caretaking environment were associated with early menarche, first sex, first pregnancy, greater number of sex partners, and shorter duration of marriage. Living with either the father or mother after separation had similar effect on reproductive development. Living with a stepfather showed a weak, but significant, association with reproductive development, however, duration of stepfather exposure was not a significant predictor of development. Difference in amount and quality of direct parental care (vs. indirect parental investment) in two- and single-parent households may be the primary factor linking family environment to reproductive development.     

Primigravidity,body weight,and costs of rearing first offspring in rhesus macaques

Body size is associated with menarche and ovarian function, but the relationship to first conception is rarely examined. We conducted a longitudinal investigation of rhesus macaques, Macaca mulatta, to determine the effect of differences in body weight on both the age at first conception and survivorship of first progeny. Young females who became pregnant weighed significantly more than peers who remained barren, with weight changes for females who successfully raised offspring no different than those for females who did not produce offspring. Infant mortality among primiparae was not significantly greater than that among multiparae, although nearly twice as high. First-born males tended to have lower survivorship than first-born female offspring. We suggest that reproductive costs encountered by primiparous females are more likely to be modulated by immature neuroendocrine function than by inexperience, small body size, or infant suckling patterns. We conclude that body size influences probability of first conception, socioendocrine factors mediate the likelihood of infant survival, and primiparous production of male progeny seems to exert a greater reproductive cost than does production of female progeny. Am. J. Primatol. 46:135–144, 1998. © 1998 Wiley-Liss, Inc.     

Age at menarche, schooling, and sexual debut in northern Malawi

Background

Age at sexual debut is a key behavioural indicator used in HIV behavioural surveillance. Early age at menarche may precipitate early sex through perceived readiness for sex, or through school drop-out, but this is rarely studied. We investigated trends and circumstances of sexual debut in relation to schooling and age at menarche.

Methods and Findings

A cross-sectional sexual behaviour survey was conducted on all individuals age 15–59 within a demographic surveillance site in Karonga District, Malawi. Time trends were assessed using birth cohorts. Survival analysis was used to estimate the median age at menarche, sexual debut and first marriage. The 25^th centile was used to define “early” sex, and analyses of risk factors for early sex were restricted to those who had reached that age, and were done using logistic regression. Of the 8232 women and 7338 men resident in the area, 88% and 78%, respectively, were seen, and, 94% and 92% of these were interviewed. The median reported age at first sex was 17.5 for women and 18.8 for men. For women, ages at menarche, sexual debut and first marriage did not differ by birth cohort. For men, age at sexual debut and first marriage decreased slightly in later birth cohorts. For both men and women increased schooling was associated with later sexual debut and a longer delay between sexual debut and first marriage, but the associations were stronger for women. Earlier age at menarche was strongly associated with earlier sexual debut and marriage and lower schooling levels. In women early sexual debut (<16 years) was less likely in those with menarche at age 14–15 (odds ratio (OR) 0.31, 95%CI 0.26–0.36), and ≥16 (OR 0.04, 95%CI 0.02–0.05) compared to those with menarche at <14. The proportion of women who completed primary school was 46% in those with menarche at <14, 60% in those with menarche at 14–15 and 70% in those with menarche at ≥16. The association between age at menarche and schooling was partly explained by age at sexual debut. The association between age at menarche and early sex was not altered by adjusting for schooling.

Conclusions

Women with early menarche start sex and marry early, leading to school drop-out. It is important to find ways to support those who reach menarche early to access the same opportunities as other young women.     

Social and biological determinants of age at first marriage in Taiwan, 1970

This study examines the social and biological determinants of age at first marriage in 2 townships in Northern Taiwan, one very rural and traditional and the other urban and modernized. Using a sample of 5707 once-married women, a path analysis examined age at first marriage as a function of age, educational status, urban origin, premarital labor force participation, and age at menarche. Age at menarche, with a positive effect on the dependent variable, was the most important direct cause of age at first marriage. This biological factor is interrelated with socioeconomic influences as predictors of age at marriage. Older cohorts of women tended to marry about 2 years earlier than did the women below 30. Urban women had a mean age at first marriage 1.76 year later than did rural women. Age at marriage steadily increases as education increases; a 4 year age differntial exists between those who have no formal education and those who have at least 12 years of education. Also, women who worked before marriage married later than those who had never worked. This study reemphasizes that in Taiwan, as elsewhere, there is a complex interplay of socioeconomic and biological factors embedded within a cultural context that influences age at first marriage for females.     

Hormonal aspects in the causation of human breast cancer: epidemiological hypotheses reviewed, with special reference to nutritional status and first pregnancy

Epidemiology of breast cancer has identified early age at menarche, late first pregnancy, low parity and late menopause as risk factors, but in addition genetic factors, height, weight and living in western countries play a significant role. The international variation in incidence is almost exclusively due to non-genetic factors. Hypotheses in prevention-oriented research are reviewed: 1. obesity-related oestrogen production as a stimulus of the tumour in postmenopausal women; 2. nutritional status and energy expenditure during puberty and adolescence, developed for fertility and fecundity and extended later to breast cancer; 3. reproductive life during early adulthood, age at first pregnancy and its specific effects on breast tissues. The message of preventability of breast cancer is that mammary epithelial differentiation should come early. Our insight concerning events in puberty and early adulthood can be consolidated in one concept on the risk of extended proliferation of breast epithelium during early adulthood in the absence of full differentiation induced by pregnancy. The combined effects of Western-type nutrition, lack of exercise and Western-type women's emancipation sets the stage for breast cancer already at a young age. Since it is unlikely that emancipated women in affluent societies will return to the original life-style of getting pregnant as soon as it is biologically possible, a novel daring way of protection has to be considered. Could a "Breast Differentiation Pill" be developed to offer protection?     

A tradeoff between reproduction and growth in contemporary Finnish women

Women have been suggested to trade growth in height for reproduction, as an earlier age at menarche and first birth seem to be related to shorter adult stature. Although women likely accrue fitness benefits by maturing and starting reproduction at young age, short adult stature may be selected against by natural and sexual selection later in their life. We studied how age at menarche and first reproduction affected adult height and whether adult height in turn was related to lifetime reproductive success in Finnish women born 1946–1958. Our results show that a delay of 1 year in age at menarche and first reproduction was related to a 0.43- and 0.20-cm increase in adult height, respectively. The sex of the first-born offspring was not related to adult height. Moreover, women gained fitness benefits by starting reproduction early but not by growing tall. These findings among Finnish women are thus compatible with tradeoffs between reproduction and growth, by showing a compromised adult height at the cost of early age at menarche and first birth. However, in these women, natural selection favored those women who traded their stature for young motherhood.     

Factors regulating the timing of puberty onset in female rhesus monkeys (Macaca mulatta): role of prenatal androgens, social rank, and adolescent body weight

This study investigated whether prenatal androgen exposure, social rank, and body weight are factors regulating pubertal development in outdoor-housed female rhesus monkeys. Subjects' mothers received injections of testosterone enanthate (20 mg/ wk), flutamide (an androgen receptor blocker, 30 mg/kg twice daily), or vehicle during Gestational Days 35/40-70 (early) or Days 105/110-140 (late). Monitoring of pubertal development began around 28 mo of age during the fall breeding season, with frequent assessment of menstruation, circulating steroids, and weight. Menarche occurred 1.5 mo later in females treated late in gestation than in females treated early in gestation. This short menarche delay occurred in females treated with androgen, flutamide, or vehicle. No effect of prenatal manipulations on first ovulation were found. Social rank was related to first ovulation but not menarche, with low-ranked females less likely than high- or middle-ranked females to ovulate at 2.5 yr than at 3.5 yr of age. Females ovulating early, around 2.5 yr, had higher pubertal body weights and body mass indexes (BMI) than did females ovulating later, suggesting that better nutritional reserves or positive energy balance affect pubertal development. Thus, social rank and likely nutritional status influenced pubertal development in this study. Hormonal manipulations had no detectable effect; instead, handling late in gestation, which may have increased maternal adrenal activity, delayed menarche. This finding contrasts with earlier studies that showed that prenatal androgens delay menarche by 4-6 mo on average. This study supports late gestation as a period of increased sensitivity to environmental insult and demonstrates that multiple factors, including prenatal programming, modulate the specific timing of pubertal events.     

Social and biological determinants of age at first marriage in Taiwan, 1970

Abstract

This study examines the social and biological determinants of age at first marriage in two townships in northern Taiwan, one very rural and traditional and the other urban and modernized. For a sample of 5,707 once‐married women a path analysis was performed in which age at first marriage was considered a function of age, educational attainment, urban origin, premarital labor‐force participation, and age at menarche. Age at menarche, with a positive effect on the dependent variable, was the most important direct cause of age at first marriage. Although exogenous variables associated with modernization (urban origin, educational attainment and younger age) had a positive direct effect on age at first marriage, they also had a negative indirect effect on age at first marriage through their negative direct effect on age at menarche.     

Heritability of age at first birth in captive olive baboons

The evolution of life history traits is a topic of growing interest in primatology. Traits associated with fertility, such as age at menarche and age at first birth, have great significance for natural selection, and knowing the genetic basis of such demographic traits may improve our understanding of population dynamics. Knowledge of the heritability of reproductive traits may also have practical implications for the management of captive breeding colonies. A maximum likelihood method was used to estimate heritability of age at first birth for a sample of female olive baboons resident at the Southwest Foundation for Biomedical Research. Only animals born at the Foundation that were caged in mixed sex groups and that had previously given birth were included in the sample (n = 316). There were 117 independent individuals and 199 individuals in 35 pedigrees composed of 2 to 26 members. Age at first birth ranged from 3.85 years to 13.11 years. Age at first birth is highly heritable (h² = 0.87) with no evidence for maternal effects or a dominance genetic component. This level of genetic variability in a fitness-related trait is contrary to evolutionary expectation and may reflect the uniform environment of a captive breeding situation. Thus, the heritability observed in this population may be taken as an upper bound for that in natural populations. © 1995 Wiley-Liss, Inc.     

Early sexual maturity among Pumé foragers of Venezuela: fitness implications of teen motherhood

Because humans have slow life histories, discussions of the optimal age at first birth have stressed the benefits of delayed reproduction. However, given the diversity of ecological, fertility, and mortality environments in which humans live, reproductive maturity is expected to be highly variable. This article uses reproductive histories to examine a pattern of early menarche and first birth among the Pume, a group of South American foragers. Age at menarche and first birth are constructed using both retrospective and cross‐sectional data for females over the age of 10 (n = 83). The objectives are first to define these patterns and then discuss their reproductive consequences. On average, Pume girls reach menarche at age 12.9, and give birth to their first child at age 15.3–15.5 (retrospective and cross‐sectional data, respectively). This populational average falls several years prior to what often is considered the human norm. Two questions are then considered. What are the infant mortality costs across a mother's reproductive career? How does surviving fertility vary with age at first birth? Results indicate that the youngest of first‐time mothers (<14) are four times more likely to loose their firstborns than older first‐time mothers (≥17). Given parity‐specific mortality rates, the optimal strategy to minimize infant mortality and maximize reproductive span is to initiate childbearing in the midteens. Women gain no additional advantage in surviving fertility by delaying childbearing until their late teens. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.     

Determinants of age at first reproduction and lifetime breeding success revealed by full paternity assignment in a male ungulate

Age at first reproduction is an important determinant of individual variation in reproductive success in ungulates, but few studies have examined its relationship with later fitness‐related traits in males. We used a long‐term individual based study of a harvested moose population to quantify the individual reproductive performance and survival of males, as well as to examine the determinants of age at first reproduction and consequences of age at first reproduction on lifetime breeding success. The probability that a male successfully reproduced at the age of two was negatively related to the mean age of adult males in the population, but the relationship weakened with increasing population size. Large antlers and large body mass relative to other males in the population increased the number of calves sired at their first successful mating season. In addition, those that successfully reproduced as two year‐olds were more likely to sire calves the next year, making them more productive at a given age compared to those that first reproduced at the age of three or older. We emphasize the importance for males to start reproducing as soon as possible in a harvested population to gain lifetime fitness benefits, as surviving the hunt is a major determinant of reproductive success in this population. We found no costs of early reproduction in males, hence leading to high individual heterogeneity in male reproductive performance. The apparent lack of reproductive costs could partly be explained by the age distribution in the population, individual variation in early‐life body mass and antler size, and differences in probabilities of being hunted of successful and unsuccessful males.     

Age at first marriage in Nepal: differentials and determinants

The aim of this paper is to investigate the differentials and determinants of female age at first marriage in rural Nepal. The life table technique was employed to calculate median age at marriage. The proportional hazard model was used to study the effect of various socioeconomic variables, and to identify the magnitude and significance of their effects on the timing of first marriage. The data were taken from a sample survey of Palpa and Rupandehi districts in rural Nepal. Both married and unmarried females of marriageable age were included in the survey. Median age at marriage was about 17 years for data from only married females, whereas it was about 18 years for data from married as well as unmarried females of marriageable age. Median age at marriage was about 16 years for uneducated females and 19 years for females educated up to intermediate or higher level. The analysis underestimates the median age at marriage for married females, probably due to right censoring. The risk of getting married early decreased gradually with increasing year-of-birth cohort. The risk of early marriage was higher among females of high socioeconomic status compared with those of low socioeconomic status. Females engaged in service married earlier than those engaged in household work. High socioeconomic status families are motivated, for religious and prestige reasons, to get their daughters married at an early age, preferably before menarche. Thus, education, occupation and age at menarche are the most powerful factors in deciding the timing of first marriage in Nepal.     

Menarche age,fatness, and fat distribution in Hawaiian adolescents

Menarche age was assessed in 93 adolescent females in a sample of public schools in East Hawaii. Native Hawaiian girls had significantly lower reported age at menarche than non-Hawaiian classmates. Age at menarche was significantly correlated with total fatness as measured by the sum of six skinfolds in girls who had reached menarche at least 2 years previous to measurement. When fatness was controlled in comparisons, the ethnic differences were not significant. Fat distribution, independent of fatness, was also significantly related to age at menarche. Socioeconomic, cultural, and admixture variables were not significantly related to age at menarche. Adiposity appears to be both a cause and a consequence of early age at menarche, with the relationship dependent on the elapsed time between menarche and measurement. This suggests that studies relating body composition to age at menarche must carefully control for the time interval between measurement and the date of menarche. © 1996 Wiley-Liss, Inc.     

Duration of ovarian hormone exposure and gynecological cancer risk in Korean women: the Korean Heart Study

BackgroundAlthough reproductive and hormonal factors – such as early menarche and late menopause – have been reported as independent risk factors for cancer, few studies have examined these factors in East Asian populations.MethodsWe performed a large prospective cohort study of 66,466 women. Ovarian hormone exposure was defined as length of time between menarche and menopause. Incidence rates for breast, ovarian, endometrial and cervical cancers were examined separately in relation to reproductive lifespan defined as age at menopause minus age at menarche. Multivariable adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) were calculated using the Cox proportional hazards model.ResultsWomen with early menarche were at increased risk for developing breast cancer (HR, 1.57, 95% CI, 1.17–2.10) for age at menarche ≤12 years compared to women with age at menarche ≥17 years. Women with late age at menopause (≥52 years) had increased risks for cancers of the breast (HR, 1.59, 95%CI, 1.11–2.28) and ovary (HR, 3.22, 95% CI, 1.09–9.55) compared to women with early menopause (≤45 years of age). Women with longer duration of ovarian hormone exposure (≥40 years) were at increased risk for developing breast cancer (HR, 2.23, 95% CI, 1.35–3.68) as well as endometrial cancer (p for trend, 0.0209).ConclusionsWe showed that longer reproductive spans are associated with an increased risk of breast and endometrial cancer in Korean women.     

Association between age at menarche and early-life nutritional status in rural Bangladesh

Age at menarche is associated with anthropometry in adolescence. Recently, there has been growing support for the hypothesis that timing of menarche may be set early in life but modified by changes in body size and composition in childhood. To evaluate this, a cohort of 255 girls aged <5 years recruited in 1988 were followed up in 2001 in Matlab, Bangladesh. The analysis was based on nutritional status as assessed by anthropometry and recalled age at menarche. Data were examined using lifetable techniques and the Cox regression model. The association between nutritional status indicators and age at menarche was examined in a multivariate model adjusting for potential confounding variables. Censored cases were accounted for. The median age at menarche was 15.1 years. After controlling for early-life predictors (birth size, childhood underweight, childhood stunting) it appeared that adolescent stunting stood out as the most important determinant of age at menarche. Adolescent stunting still resonates from the effect of stunting in early childhood (OR respectively 2.63 (p<0.01 CI: 1.32-5.24) and 8.47 (p<0.001 CI: 3.79-18.93) for moderately and severely stunted under-fives as compared with the reference category). Birth size was not a significant predictor of age at menarche. It is concluded that age at menarche is strongly influenced by nutritional status in adolescence, notably the level of stunting, which is in turn highly dependent on the level of stunting in early childhood. A 'late' menarche due to stunting may be detrimental for reproductive health in case of early childbearing because of the association between height and pelvic size.     

Early-life conditions and age at first pregnancy in British women

There is growing evidence that the reproductive schedules of female mammals can be affected by conditions experienced during early development, with low parental investment leading to accelerated life-history strategies in the offspring. In humans, the relationships between early-life conditions and timing of puberty are well studied, but much less attention has been paid to reproductive behaviour. Here, we investigate associations between early-life conditions and age at first pregnancy (AFP) in a large, longitudinally studied cohort of British women (n = 4553). Low birthweight for gestational age, short duration of breastfeeding, separation from mother in childhood, frequent family residential moves and lack of paternal involvement are all independently associated with earlier first pregnancy. Apart from that of birthweight, the effects are robust to adjustment for family socioeconomic position (SEP) and the cohort member's mother's age at her birth. The association between childhood SEP and AFP is partially mediated by early-life conditions, and the association between early-life conditions and AFP is partially mediated by emotional and behavioural problems in childhood. The overall relationship between early-life adversities and AFP appears to be approximately additive.     

Reproductive development and behavior of captive female chimpanzees

The reproductive histories and behavior of six chimpanzees were analyzed in order to evaluate the female reproductive pattern. This analysis indicated that captive females undergo an earlier menarche and an acceleration of subsequent reproductive phases as compared to wild chimpanzees. Menarche occurred between 7.7–9.3 years of age and first conceptions occurred between 8.2–10.7 years of age. Changes in the females' sex skins across menarche, pregnancy, and the menstrual cycle were also evaluated. The fluctuation in sex skin size was shown to have a marked effect on the occurrence of sexual behavior. In addition, the social context and relative familiarity of the chimpanzees affected the choice of sexual partners.