Adolescent girls are an important target group for micronutrient interventions particularly in Sub-Saharan Africa where adolescent pregnancy and micronutrient deficiencies are common. When consumed in sufficient amounts and at levels appropriate for the population, fortified foods may be a useful strategy for this group, but little is known about their effectiveness and timing (regarding menarche), particularly in resource-poor environments. We evaluated the effect of consuming multiple micronutrient-fortified biscuits (MMB), sold in the Ghanaian market, 5 d/week for 26 weeks compared with unfortified biscuits (UB) on the micronutrient status of female adolescents. We also explored to what extent the intervention effect varied before or after menarche. Ten2Twenty-Ghana was a 26-week double-blind, randomised controlled trial among adolescent girls aged 10–17 years (n 621) in the Mion District, Ghana. Biomarkers of micronutrient status included concentrations of Hb, plasma ferritin (PF), soluble transferrin receptor (TfR) and retinol-binding protein (RBP), including body-iron stores. Intention-to-treat analysis was supplemented by protocol-specific analysis. We found no effect of the intervention on PF, TfR and RBP. MMB consumption did not affect anaemia and micronutrient deficiencies at the population level. MMB consumption increased the prevalence of vitamin A deficiency by 6·2 % (95 % CI (0·7, 11·6)) among pre-menarche girls when adjusted for baseline micronutrient status, age and height-for-age Z-score, but it decreased the prevalence of deficient/low vitamin A status by −9·6 % (95 % CI (−18·9, −0·3)) among post-menarche girls. Consuming MMB available in the market did not increase iron status in our study, but reduced the prevalence of deficient/low vitamin A status in post-menarcheal girls.

Recent developments in the application life history theory to human development indicate two fundamental dimension of the early environment – harshness and unpredictability – are key regulators life history strategies. Few studies have examined the manner with which these dimensions influence development, though age at menarche (AAM) and age at first sexual intercourse have been proposed as possible mechanisms among women. Data from the Avon Longitudinal Study of Parents and Children (N = 3,645) were used to examine direct and indirect effects of harshness (financial difficulties) and unpredictability (paternal transitions) on lifetime and past year sexual partners during adolescence and young adulthood. Genetic confounding was addressed using an AAM polygenic score (PGS) and potential gene-by-environment interactions were also evaluated using the PGS. Path model results showed only harshness was directly related to AAM. Harshness, unpredictability, and AAM were indirectly related to lifetime and past year sexual partner number via age at first sexual intercourse. The PGS did not account for any of the associations and no significant interactions were detected. Implications of these results for developmental models derived from life history theory are discussed as well as the role of PGSs in gene–environment interplay research.

Father absence has a small but robust association with earlier age at menarche (AAM), likely reflecting both genetic confounding and an environmental influence on life history strategy development. Studies that have attempted to disambiguate genetic versus environmental contributions to this association have shown conflicting findings, though genomic-based studies have begun to establish the role of gene–environment interplay in the father absence/AAM literature. The purpose of this study was to replicate and extend prior genomic work using the Avon Longitudinal Study of Parents and Children (ALSPAC), a prospective longitudinal cohort study (N = 2,685), by (a) testing if an AAM polygenic score (PGS) could account for the father absence/AAM association, (b) replicating G×E research on lin-28 homolog B (LIN28B) variation and father absence, and (c) testing the G×E hypothesis using the PGS. Results showed that the PGS could not explain the father absence/AAM association and there was no interaction between father absence and the PGS. Findings using LIN28B largely replicated prior work that showed LIN28B variants predicted later AAM in father-present girls, but this AAM-delaying effect was absent or reversed in father-absent girls. Findings are discussed in terms genetic confounding, the unique biological role of LIN28B, and using PGSs for G×E tests.

Nearly 80% of new cases of myopia arise between 9 and 13 years old when puberty development also progresses rapidly. However, little is known about the association between myopia and puberty. We aim to evaluate the association between myopia and menarche, the most important puberty indicator for girls, and to test whether menarche could modify the effects of myopia-related behaviors. The participants came from two consecutive national surveys conducted in 30 provinces in mainland China in 2010 and 2014. We included 102,883 girls (61% had experienced menarche) aged 10–15 years. Risk behaviors for myopia which included sleep duration, homework time, and outdoor activity were measured by self-administrated questionnaire. Myopia was defined according to a validated method, and its relationships with menarche status and behaviors were evaluated by robust Poisson regression models based on generalized estimated equation adjusting for cluster effect of school. We found that postmenarche girls were at 13% (95% confidence interval: 11%–16%) higher risk of myopia than premenarche girls, after adjusting for exact age, urban–rural location, survey year, and four behavioral covariates. Short sleep duration (<7 h/d), long homework time (>1 h/d) and low frequency of weekend outdoor activity tended to be stronger (with higher prevalence ratios associated with myopia) risk factors for myopia in postmenarche girls than in premenarche girls, and their interaction with menarche status was all statistically significant (P < 0.05). Overall, our study suggests that menarche onset may be associated with increased risk of myopia among school-aged girls and could also enhance girls’ sensitivity to myopia-related risk behaviors.

Menarche and menopause are two major components of a woman’s reproductive life. Ages at menarche and menopause vary widely between and within populations and are influenced by various factors, both genetic and environmental. The present community-based cross-sectional investigation aimed to assess the association between ages at menarche and natural menopause among women belonging to the indigenous Rajbanshi population of North Bengal, India. The investigation was carried out from January 2015 to May 2015 among 510 Rajbanshi women aged between 45 and 55 years residing in the district of Darjeeling, West Bengal, India. A structured schedule was used to collect data on ages at menarche and natural menopause, marital status, parity, education, age of first and last pregnancies, duration of breastfeeding, nature of occupation, health status, smoking and monthly family income. Anthropometric measurements of height and weight were recorded and Body Mass Index (BMI) calculated. The statistical analyses, which included descriptive statistics and binary logistic regression (BLR), were done using SPSS. The women’s mean age of menarche and median age of natural menopause were 12.52 years and 50 years, respectively. The BLR analysis indicated that education, age at first pregnancy had significant effects on the age at natural menopause among women who experienced menarche at <12 years of age (p<0.05). In the case of women who attained menarche at ≥12 years of age, marital status, age at last pregnancy, parity, education, duration of breastfeeding, smoking, occupation, monthly income and BMI had a greater influence on age at natural menopause. There appears to be an indirect association between age at menarche and age at natural menopause, along with different predictor variables, among the Rajbanshi women.

This article uses the mean age at menarche of women in China as an indicator of changes in the standard of living during the 20th century. It discusses the difficulties of using this indicator. It finds that the mean age of menarche stagnated at 16 to 17 years for women born during the period between the 1880s and 1930s. The age at menarche decreased in some urban areas, indicating improving living standards in, for example, Beijing and Shanghai. The mean age at menarche increased for 1940s’ birth cohorts, in relation not only to the warfare of the 1940s but also the famine of 1959–1962. The mean age at menarche decreased in a sustained way for women born during the 1950s to early 2000s. The decrease is associated with increasing educational attainment since the 1940s and also improvements in nutrition, hygiene and healthcare.

Associations have been shown between father’s absence and menarcheal age, but most studies have focused on absence resulting from divorce, abandonment or death. Little research has been conducted to evaluate the effect on menarcheal age of paternal absence through migrant work. In a sample of 400 middle school students, this study examined the association between paternal migrant work and menarcheal age against a backdrop of extensive rural-to-urban migration in China. Data were collected through a self-reported questionnaire, including social-demographic characteristics, aspects of family relationships, information about father’s migrant work and age at menarche. After adjusting for BMI, parent marital status and perceived relationship with mother, lower self-perceived quality of father–daughter relationship (both ‘father present, relationship poor’ and ‘father absent, relationship poor’) and lower frequency of contact with the father were associated with higher odds for early menarche. These findings suggest that the assumption that father’s absence for work influences the timing of menarche needs to be examined in the context of the quality of the father–daughter relationship and paternal care, which appear to play a critical role in the timing of menarche. These findings also emphasize the importance of enhancing paternal involvement and improving father–daughter relationships in the development of appropriate reproductive strategy in daughters.

Animal and cross-sectional epidemiological studies suggest that prenatal lead exposure is related to delayed menarche, but this has not been confirmed in longitudinal studies. We analyzed this association among 200 girls from Mexico City who were followed since the first trimester of gestation. Maternal blood lead levels were analyzed once during each trimester of pregnancy, and daughters were asked about their first menstrual cycle at a visit between the ages of 9.8 and 18.1 years. We estimated hazard ratios (HRs) and 95% confidence intervals (CI) for probability of menarche over the follow-up period using interval-censored Cox models, comparing those with prenatal blood lead level ⩾5 µg/dl to those with prenatal blood lead <5 µg/dl. We also estimated HRs and 95% CI with conventional Cox regression models, which utilized the self-reported age at menarche. In adjusted analyses, we accounted for maternal age, maternal parity, maternal education, and prenatal calcium treatment status. Across trimesters, 36−47% of mothers had blood lead levels ⩾5 µg/dl. Using interval-censored models, we found that during the second trimester only, girls with ⩾5 µg/dl prenatal blood lead had a later age at menarche compared with girls with prenatal blood lead levels <5 µg/dl (confounder-adjusted HR=0.59, 95% CI 0.28–0.90; P=0.05). Associations were in a similar direction, although not statistically significant, in the conventional Cox regression models, potentially indicating measurement error in the self-recalled age at menarche. In summary, higher prenatal lead exposure during the second trimester could be related to later onset of sexual maturation.

Childhood intake of animal foods is associated with age at first menstrual period (menarche). It is unknown whether the micronutrients present in these foods could explain this association. Our objective was to investigate the associations of micronutrient status biomarkers in middle childhood with age at menarche. We quantified circulating Hb, ferritin, mean corpuscular volume, Zn, vitamin B12, erythrocyte folate and retinol in 1464 pre-menarcheal girls aged 5–12 years in Bogotá, Colombia, and followed them for a median 5·7 years for the occurrence and date of menarche. We estimated median age at menarche and hazard ratios (HR) with 95 % CI by levels of each biomarker with use of Kaplan–Meier survival probabilities and Cox regression, respectively. Median age at menarche was 12·4 years. Middle childhood Hb was inversely related to age at menarche whereas plasma ferritin was positively associated with this outcome in a linear manner. HR of menarche for every 1 sd of Hb (11 g/l) and ferritin (23·2 µg/l) were 1·11 (95 % CI 1·04, 1·18; P=0·001) and 0·94 (95 % CI 0·88, 0·99; P=0·02), respectively, after adjustment for baseline age, C-reactive protein concentration, maternal age at menarche and parity and socioeconomic status. The association with ferritin was stronger in girls aged 9–10 years at baseline. Additional adjustment for baseline height- and BMI-for-age did not change the results. We conclude that higher Fe status in middle childhood is related to later age at menarche whereas Hb concentrations are inversely associated with age at onset of menses.

Intrauterine exposure to the rainy season in the tropics may be accompanied by high rates of infection and nutritional deficiencies. It is unknown whether this exposure is related to the extrauterine timing of development. Our aim was to evaluate the relations of prenatal exposure to the rainy season and altitude of residence with age at menarche. The study included 15,370 girls 10 to <18 years old who participated in Colombia’s 2010 National Nutrition Survey. Primary exposures included the number of days exposed to the rainy season during the 40 weeks preceding birth, and altitude of residence at the time of the survey. We estimated median menarcheal ages and hazard ratios with 95% confidence interval (CI) according to exposure categories using Kaplan–Meier cumulative probabilities and Cox proportional hazards models, respectively. All tests incorporated the complex survey design. Girls in the highest quintile of gestation days exposed to the rainy season had an earlier age at menarche compared with those in the lowest (adjusted hazard ratios (HR)=1.08; 95% CI 1.00–1.18, P-trend=0.03). Girls living at altitudes ⩾2000 m had a later age at menarche compared with those living <1000 m (adjusted HR=0.88; 95% CI 0.82–0.94, P-trend <0.001). The inverse association between gestation days during the rainy season and menarche was most apparent among girls living at altitudes ⩾2000 m (P, interaction=0.04). Gestation days exposed to the rainy season and altitude of residence were associated with the timing of sexual maturation among Colombian girls independent of socioeconomic status and ethnicity.

The decline in age of pubertal timing has serious public health implications ranging from psychosocial adjustment problems to a possible increase in reproductive cancers. One biologically plausible explanation for the decline is a decrease in exposures to infections. To systematically review studies that assess the role of infection in pubertal timing, Medline, Web of Science and EMBASE were systematically searched and retrieved studies were reviewed for eligibility. Eligible studies examined the association between infections, including microbial exposures, and physical pubertal characteristics (breast, genitalia and pubic hair development) or age at menarche. We excluded studies that were published in a language other than English, focused on precocious puberty, were case studies, and/or included youth with autoimmune diseases. We report on study design, population characteristics, measurement of infection and puberty and the main effects of infection on pubertal development. Based on our search terms we identified 1372 unique articles, of which only 15 human and five animal studies met our eligibility criteria. Not all studies examined all outcomes. Infection was associated with later breast development (4/4 human studies), with less consistent evidence for genitalia and pubic hair development. Seven studies assessed age at menarche with inconsistent findings (three supporting later, four no association). We conclude that a small but consistent literature supports that infection is associated with later breast development; the evidence for other pubertal events and age at menarche is less clear. Where fewer childhood infections coincide with the rise in incidence of hormone-related cancers.

Our aim in this study is to describe the characteristics of sexual development in twins and estimate the role of heritability and environmental factors as causes of certain sexual disorders. Two hundred and ten adult same-sex twin pairs (92 monozygotic [MZ] female, 41 MZ male, 55 dizygotic [DZ] female and 22 DZ male pairs) were involved in the study. Data were collected in 1982 by self-administered questionnaires that included items on sexual maturation, sexual life, contraception, mutual sexual activity within twin pairs and alcohol use. The ratio of married to unmarried twins was nearly the same in MZs and DZs, with the exception that the divorce rate was higher in MZ female twins (14%), and DZ and male twins were slightly more likely to be single. Menarche was later in twins compared to non-twin Hungarian women. 57% of MZs experienced menarche within 3 months of each other, 77% within 6 months while it occurred for 30% and 43% respectively in DZs. The first seminal emission indicated some delay in male twins compared with the Hungarian general population sample. MZ first kisses occurred later than DZ's first kisses. The same was true for the first petting, masturbation and first sexual intercourse. Anorgasmy is 27% heritable but the estimate is not statistically significant. Concordance rate for premature ejaculation in MZs was greater than in DZs but the structural equation model showed significant misfit. Age at menarche appeared to be strongly heritable.