Is the timing of menarche correlated with mortality and fertility rates?

Self-reported history of breastfeeding in relation to recalled age at menarche in the United States

Menarche is a key life history event that shapes the female reproductive trajectory and is important to the study of human biology because of the associated epidemiological and social consequences later in life. Our question is whether breastfeeding is associated with the variation in timing of menarche. Using data from a college-aged female student population from Amherst, MA, we examined whether having been breastfed was associated with age at menarche. Of the 340 female participants with information on breastfeeding during infancy, we found that women who were breastfed (n = 286) had an adjusted mean age of menarche of 12.53 years (SE 0.09), while those who were not breastfed (n = 54) had an adjusted mean age of menarche of 12.04 years (SE 0.20; p < 0.03). We propose further research that explores a finer distinction between formula-fed, mixed-fed or predominantly breastfed infants, duration of breastfeeding and age at menarche.

Adipose development is consistent across hunter-gatherers and diverges from western references

Despite agreement that humans have evolved to be unusually fat primates, adipose patterning among hunter-gatherers has received little empirical consideration. Here we consider the development of adiposity among four contemporary groups of hunter-gatherers, the Aka, Savanna Pumé, Ju'/Hoansi and Agta using multi-level generalized additive mixed modelling to characterize the growth of tricep skinfolds from early childhood through adolescence. In contrast to references, hunter-gatherers show several consistent patterns: (i) children are lean with little fat accumulation; (ii) no adiposity rebound at 5 years is evident; (iii) girls on average have built 90% of their body size, and reach menarche when adiposity is at its maximum velocity; and (iv) a metabolic trade-off is evident in young, but not older children, such that both boys and girls prioritize skeletal growth during middle childhood, a trade-off that diminishes during adolescence when height velocity increases in pace with fat accumulation. Consistent results across hunter-gatherers living in diverse environments suggest that these patterns reflect a general forager pattern of development. The findings provide a valuable baseline for adipose development not apparent from reference populations. We emphasize both generalized trends among hunter-gatherers, and that inter-populational differences point to the plasticity with which humans organize growth and development.

Mean age at menarche and climate variables on a global scale

OBJECTIVES

Cross-population variation in age at menarche is related to many factors. The purpose of this study was to examine climate variables in relation to mean age at menarche among 87 modern human populations. We hypothesized a later age at menarche among populations living in areas with high precipitation variability, heavy seasonal rainfall, and high temperatures year-round due to water-borne diseases and periods of resource scarcity.

METHODS

Using a comparative dataset, we examined geospatial distribution and climate variables in relation to age at menarche for 87 modern human populations.

RESULTS

We found the strongest predictor of a later age at menarche was higher fertility followed by a later mean age at death. In addition, higher annual rainfall, higher precipitation seasonality, and lower annual mean temperature were moderate predictors of age at menarche.

CONCLUSIONS

We propose that later ages at menarche in countries with high fertility may be a life-history strategy developed in response to climatic conditions that have resulted in higher immunological load. In these conditions, females may prioritize growth rather than reproduction. Shifts in climate and global population growth may change the future biological landscape of age at menarche.

From the Ground Up: A Multidisciplinary Approach to Past Fertility and Population Narratives

Population dynamics form a crucial component of human narratives in the past. Population responses and adaptations not only tell us about the human past but also offer insights into the present and future. Though an area of substantial interest, it is also one of often limited evidence. As such, traditional techniques from demography and anthropology must be adapted considerably to accommodate the available archaeological and ethnohistoric data and an appropriate inferential framework must be applied. In this article, I propose a ground-up, multidisciplinary approach to the study of past population dynamics. Specifically, I develop an empirically informed path diagram based on modern fertility interactions and sources of past environmental, sociocultural, and biological evidence to guide high-resolution case studies. The proposed approach is dynamic and can evolve in response to data inputs as case studies are undertaken. In application, this approach will create new knowledge of past population processes which can greatly enhance our presently limited knowledge of high-frequency, small-scale demographic fluctuations, as well as contribute to our broader understanding of significant population disturbances and change throughout human history.

Assessment of Prior Infection With Hepatitis B Virus and Fecundability in Couples Planning Pregnancy

IMPORTANCE

The association of hepatitis B virus (HBV) infection with reduced fecundability among reproductive-aged couples lacks large-population, in-depth study evidence.

OBJECTIVE

To investigate the association of HBV infection with time to pregnancy in couples planning pregnancy, and to explore whether this association varied by gravidity, health statuses, or lifestyles.

DESIGN, SETTING, AND PARTICIPANTS

This is a population-based cohort study of Chinese couples participating in the National Free Preconception Check-up Projects during 2015 to 2017. They were planning pregnancy and were followed-up every 3 months until getting pregnant, as confirmed by gynecologic ultrasonography, or were followed-up for 1 year. Data were analyzed between March 1, 2022, and September 30, 2022.

MAIN OUTCOMES AND MEASURES

The main outcome was time to pregnancy, assessed using fecundability hazard ratios (HRs). The Cox proportional hazards regression models were used to estimate the association of HBV infection with fecundability.

RESULTS

Among 2 419 848 couples (mean [SD] age, 27.87 [5.20] years for women and 29.58 [5.50] years for men), 126 728 women (5.24%) and 156 572 men (6.47%) were infected with HBV. Compared with the HBV-negative group, the fecundability of both women and men in the HBV-positive group decreased by 5% (HR, 0.95; 95% CI, 0.94-0.95). Compared with couples in which both partners were HBV negative, the fecundability of those in which both partners were HBV positive declined by 6% (HR, 0.94; 95% CI, 0.93-0.96) among all couples, by 3% (HR, 0.97; 95% CI, 0.95-0.99) among nulligravidas couples, and by 7% (HR, 0.93; 95% CI, 0.91-0.95) among multigravidas couples. Both the female-male and couple models suggested that the association of HBV infection with decreased fecundability was more pronounced in couples with multigravidas. The negative association was greater in people with overweight and obesity and was inconsistent in certain subgroups; in particular, it was more pronounced in women with reproductive tract infections, normal fasting plasma glucose, and no alcohol intake and in men with normal blood pressure.

CONCLUSIONS AND RELEVANCE

In this population-based cohort study, HBV infection was associated with decreased fecundability in a general reproductive-aged population, especially in couples with multigravidas. For women and men with certain health statuses and lifestyles, a comprehensive consideration of this association is recommended to provide personalized fertility guidance.

Psychosocial and energetic factors on human female pubertal timing: a systematized review

Childhood psychosocial stressors have been proposed to favour fast life history strategies promoting earlier puberty in females. However, studies demonstrating this association often do not elucidate causal mechanisms, nor account for greater childhood energetic availability - also known to promote rapid growth and earlier puberty. To assess the extent to which such confounding has been considered, we conducted a systematized review to identify studies examining measures of both prepubertal growth (e.g. weight, height) and psychosocial stressors (e.g. adversity, father absence) in relation to female pubertal timing. A total of 1069 non-duplicated studies were identified across five databases. Twenty studies met selection criteria for critical review following independent screening of titles, abstracts and manuscripts. Within these studies, measures indicative of rapid childhood growth were more consistently associated with earlier pubertal timing than were measures of psychosocial stress. We discuss future research directions to investigate the impact of psychosocial stress on pubertal timing more robustly, including methodological and mechanistic considerations, and contextualization of findings by socioecological environments.

Increased Menopausal Age Reduces the Risk of Parkinson's Disease: A Mendelian Randomization Approach

BACKGROUND

Studies of Parkinson's disease (PD) and the association with age at menarche or menopause have reported inconsistent findings. Mendelian randomization (MR) may address measurement errors because of difficulties accurately reporting the age these life events occur.

OBJECTIVE

We used MR to assess the association between age at menopause and age at menarche with PD risk.

METHODS

We performed inverse variant-weighted (IVW) MR analysis using external genome-wide association study (GWAS) summary data from the United Kingdom biobank, and the effect estimates between genetic variants and PD among two population-based studies (Parkinson's disease in Denmark (PASIDA) study, Denmark, and Parkinson's Environment and Gene study [PEG], United States) that enrolled 1737 female and 2430 male subjects of European ancestry. We, then, replicated our findings for age at menopause using summary statistics from the PD consortium (19 773 women), followed by a meta-analysis combining all summary statistics.

RESULTS

For each year increase in age at menopause, the risk for PD decreased (odds ration [OR], 0.84; 95% confidence interval [CI], 0.73-0.98; P = 0.03) among women in our study, whereas there was no association among men (OR, 0.98; 95% CI, 0.85-1.11; P = 0.71). A replication using summary statistics from the PD consortium estimated an OR of 0.94 (95% CI, 0.90-0.99; P = 0.01), and we calculated a meta-analytic OR of 0.93 (95% CI, 0.89-0.98; P = 0.003). There was no indication for an association between age at menarche and PD (OR, 0.75; 95% CI, 0.44-1.29; P = 0.29).

CONCLUSIONS

A later age at menopause was associated with a decreased risk of PD in women, supporting the hypothesis that sex hormones or other factors related to late menopause may be neuroprotective in PD. © 2021 International Parkinson and Movement Disorder Society.

Longitudinal association of dietary sources of animal and plant protein throughout childhood with menarche

Background

Inconsistent findings have been reported for associations between protein intake and age at menarche. We aimed to investigate the association between intake of protein and protein-containing food groups during childhood with menarche among Iranian girls.

Methods

Girls aged 6–18 years who did not experience menarche in the third or fourth examination cycles of the Tehran Lipid and Glucose Study were selected and were followed to the fifth examination cycle. Daily intakes of protein from different animal/plant sources and ten protein-containing food groups were assessed using a food frequency questionnaire at baseline (the third or fourth examination cycles). Occurrence of menarche and its onset age were asked during each examination cycle. Cox proportional hazards regression was used to estimating hazard ratios (HRs) and 95% confidence interval (95%CI) for the occurrence of menarche per one standard deviation (SD) of dietary intakes. Logistic regression was also used to estimate the odds of reaching menarche ≤12 years.

Results

During the study, 147(61%) of girls reached menarche, the median age at menarche was 12 years. The adjusted HRs (95% CI) for the occurrence of menarche per one-SD of dietary intakes were 0.68 (0.48, 0.98; p = 0.040) for plant protein and 1.36 (1.01, 1.84; p = 0.042) for animal protein after adjusting for baseline age, BMI Z-score, energy intake, and mother’s early menarche and education. Substituting 10-g animal protein with plant protein was associated with a 16% (95%CI: 5–25%; p = 0.006) lower risk of menarche. Dietary intakes of poultry (adjusted HR: 1.35; 95% CIs: 1.00–1.82; p = 0.049) and low-fat dairy (adjusted HR: 1.20; 95%CIs: 0.99–1.46; p = 0.064) were marginally associated with the increased risk of menarche. However, the odds of early menarche was significant only for plant protein (adjusted odds ratio = 0.39; 95% CI: 0.16–0.96; p = 0.040).

Conclusions

Our findings indicate that the risk of menarche increases by higher intakes of animal protein and decreases by plant protein. Intakes of poultry and low-fat dairy associate with a higher risk of menarche. The odds of menarche occurrence ≤12 years reduces by higher intakes of plant protein.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02670-8.

Timing and determinants of age at menarche in low-income and middle-income countries

INTRODUCTION

Understanding the timing and determinants of age at menarche is key to determining potential linkages between onset of puberty and health outcomes from a life-course perspective. Yet, we have little information in low-income and middle-income countries (LMICs) mainly due to lack of data. The aim of this study was to analyse trends in the timing and the determinants of menarche in LMICs.

METHODS

Using 16 World Fertility Survey and 28 Demographic and Health Surveys (DHS) from 27 countries, we analysed cohort trends and used fixed-effects models for DHS surveys to investigate sociodemographic and regional effects in the timing of age at menarche.

RESULTS

Trends of the mean age at menarche across time within and between countries show a declining or stalling path. Results of the determinant modelling show the relationship with wealth changes over time although not consistently across countries. We see a shift from poorer women having earlier menarche in earlier surveys to richer women having earlier menarche in later surveys in Indonesia, the Philippines and Yemen, while in Egypt, the reverse pattern is evident.

CONCLUSIONS

There is a considerable gap in both literature and data on menarche. We see a trend which is declining rapidly (from 14.66 to 12.86 years for the 1932 and 2002 cohorts, respectively), possibly at a faster pace than high-income countries and with a strong link to socioeconomic status. This study calls for menarche questions to be included in more nationally representative surveys and greater use of existing data because of its impact on life-course health in fast-ageing settings. Further studies will need to investigate further the use of the age at menarche as an indicator of global health.

Socio-Ecological Challenges as Modulators of Women's Reproductive Trajectories

Amenorrhea, anovulatory cycles, miscarriages, and other reproductive outcomes are often seen as pathological. Life history theory, in contrast, treats those outcomes as adaptations that helped women optimize the timing of reproductive ventures across our evolutionary history. Women's bodies adjust their reproductive strategies in response to socio-ecological conditions, a process mediated by the hypothalamic-pituitary-adrenal axis (HPAA). Here, we review the links between socio-ecological conditions, HPAA activity, and the pace of women's reproductive transitions such as puberty, age at first birth, interbirth interval, and perimenopause. We also discuss the HPAA's role as a modulator of reproductive function: It not only suppresses it but may also prime women's bodies for future reproductive ventures. We conclude by reviewing challenges and opportunities within our subfield, including the need for transdisciplinary teams to develop longitudinal studies to improve our understanding of women's reproductive trajectories and outcomes from the moment they are conceived.

Medieval menarche: Changes in pubertal timing before and after the Black Death

OBJECTIVES

Bioarcheological evidence suggests stature increased in males but decreased in females after the Black Death (1348-1350 CE). Because tradeoffs between growth and reproduction can result in earlier ages at menarche and lower limb length, we assess menarcheal age between 1120 and 1540 CE to better understand the health of medieval adolescent females before and after the plague.

MATERIALS AND METHODS

Our sample comprises 74 adolescent females from St. Mary Spital, London (1120-1540 CE) within the age range during which menarche occurs (10-25 years). They were assessed as being pre- or post-menarcheal and divided into three groups: Early Pre-Black Death (n = 13), Late Pre-Black Death (n = 38), and Post-Black Death (n = 23). Changes in the ages of pre- and post-menarcheal females were assessed using Mann-Whitney tests.

RESULTS

The average age of post-menarcheal females increased from the Early- to Late Pre-Black Death periods and declined after the Black Death.

CONCLUSIONS

Short stature can reflect unfavorable growth environments, while younger menarcheal age indicates improved living conditions. The paradoxical pattern of female, but not male, stature reduction after the Black Death might reflect the association of early menarche with lower limb length and signal that adolescent females experienced improved health conditions after the epidemic. Our focus on pre- and post-menarche within a limited age span provides a novel approach for inferring average ages of menarche over time. Pathways to skeletal development and reproductive investment are part of an integrated system, providing a bridge between life history research in bioarchaeology and human biology.

A Systematic Literature Review of Factors Affecting the Timing of Menarche: The Potential for Climate Change to Impact Women's Health

Menarche is the first occurrence of a woman’s menstruation, an event that symbolizes reproductive capacity and the transition from childhood into womanhood. The global average age for menarche is 12 years and this has been declining in recent years. Many factors that affect the timing menarche in girls could be affected by climate change. A systematic literature review was performed regarding the timing of menarche and four publication databases were interrogated: EMBASE, SCOPUS, PubMed, and Cochrane Reviews. Themes were identified from 112 articles and related to environmental causes of perturbations in menarche (either early or late), disease causes and consequences of perturbations, and social causes and consequences. Research from climatology was incorporated to describe how climate change events, including increased hurricanes, avalanches/mudslides/landslides, and extreme weather events could alter the age of menarche by disrupting food availability or via increased toxin/pollutant release. Overall, our review revealed that these perturbations in the timing of menarche are likely to increase the disease burden for women in four key areas: mental health, fertility-related conditions, cardiovascular disease, and bone health. In summary, the climate does have the potential to impact women’s health through perturbation in the timing of menarche and this, in turn, will affect women’s risk of disease in future.