Secular trend in age at menarche in China: a case study of two rural counties in Anhui Province

Association of female reproductive and hormonal factors with gallbladder cancer risk in Asia: A pooled analysis of the Asia Cohort Consortium

The female predominance of gallbladder cancer (GBC) has led to a hypothesis regarding the hormone-related aetiology of GBC. We aimed to investigate the association between female reproductive factors and GBC risk, considering birth cohorts of Asian women. We conducted a pooled analysis of 331,323 women from 12 cohorts across 4 countries (China, Japan, Korea, and Singapore) in the Asia Cohort Consortium. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) to assess the association between reproductive factors (age at menarche, parity, age at first delivery, breastfeeding, and age at menopause) and GBC risk. We observed that a later age at menarche was associated with an increased risk of GBC (HR 1.4, 95% CI 1.16-1.70 for 17 years and older vs. 13-14 years), especially among the cohort born in 1940 and later (HR 2.5, 95% CI 1.50-4.35). Among the cohort born before 1940, women with a later age at first delivery showed an increased risk of GBC (HR 1.56, 95% CI 1.08-2.24 for 31 years of age and older vs. 20 years of age and younger). Other reproductive factors did not show a clear association with GBC risk. Later ages at menarche and at first delivery were associated with a higher risk of GBC, and these associations varied by birth cohort.

Knowledge of peri-menarcheal changes and a comparative analysis of the age at menarche among young adolescent school girls in urban and rural Cameroon

Background

Menarche is an expected event that occurs during the development of every normal young girl. We designed this study to evaluate the knowledge of young school girls on puberty, menarche, and menstruation, and to update data on the age at menarche in a rural and urban setting in Cameroon.

Methods

We conducted a cross-sectional survey from February to March 2017, targeting female students aged 9 to 16 years in Yaoundé (urban) and Bamougoum (rural). Participants were included using a randomised cluster sampling and data collected using an auto-administrable questionnaire. Student t-test or the Kruskal-Wallis test was used to compare means, and the odds ratio used as the measure of association between age at menarche and selected covariates.

Results

1157 participants were included in the study; 49.3% from an urban setting and 50.7% from a rural setting. Regarding the knowledge of our participants on puberty, menarche, and menstruation, 67.20% of rural participants had good knowledge, whereas only 46.00% had good knowledge in the urban setting. Mean age at menarche was 12.76 ± 1.33 years, with the mean age at menarche in the urban setting of 12.48 ± 1.12 years and the rural setting of 13.03 ± 1.46 years. Mean age at menarche was significantly lower in participants aged below 14 years (p-value = 0.000), those with both parents alive (p-value = 0.0461), those whose fathers had skilled occupations (p-value = 0.005), those of urban resident (p-value = 0.000), and those who watched TV everyday (p-value = 0.030). Urban residence and age below 14 years were significantly associated with an earlier onset of menarche.

Conclusion

Rural participants had better knowledge of puberty, menarche, and the menstrual cycle than their counterparts in the urban setting. The mean age at menarche over the last two decades has dropped by 7.4 and 4.2 months per decade in urban and rural Cameroon respectively. Mean age at menarche varies significantly with age group, urban/rural residence, state of both parents (both alive/at least one dead), occupation of the father, and frequency of watching TV. Age and urban/rural residence are associated with age at onset of menarche. The continually declining age at menarche is an alarm for future early menarche-linked morbidities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-020-09787-y.

The relationship between short stature and menstrual pattern in a large cohort of Iranian girls

The aim of this study was to investigate the relationship between stature and menstrual pattern. Nine hundred and seventy six girls were selected from regions within two cities in north-eastern Iran in 2015. They were assessed with respect to: their stature and menstrual pattern, age of menstruation, severity of dysmenorrhoea, duration of their menstrual cycle and flow. 841 girls had experienced menarche. 10.5% had a short stature. There were significant differences in age, height, weight and body mass index between those who had experienced their first menstrual cycle and others (p < .001). There were weak and negative correlation between age of menarche and height percentiles (r  =  -0.12, p < .001). Premenstrual syndrome, duration of menstruation cycle and bleeding period did not differ between these two groups (p > .05). We found that dysmenorrhoea was significantly influenced by height. Although the mean age at menarche was statistically significant among different statures, the range was narrow (12.2-12.7). Further studies considering environmental factors, including socioeconomic status and nutrition concurrently, are also required.Impact statementWhat is already known on this subject? Various menstrual characteristics, including age of menarche, severity of dysmenorrhoea and duration of menstrual period may be associated with height. But, there have been few studies on the relationship between short stature and its impact on health status and menstrual patterns in adolescents.What do the results of this study add? There were significant differences in age, height, weight and body mass index between adolescent girls who had experienced their first menstrual cycle, and others. There were weak, negative, significant correlations between age of menarche and height percentiles. Dysmenorrhoea was significantly influenced by height.What are the implications of these findings for clinical practice and/or further research? Life style modification and nutritional interventions that optimise the height of girls may resolve their menstrual problems and dysmenorrhoea.

Constrained Choices? Menstrual Health and Hygiene Needs Among Adolescents in Mumbai Slums

Menstruation, an essential and healthy biological function, is cloaked in a culture of silence. Sociocultural norms at the family and community level play a pivotal role in shaping how young unmarried women understand and manage their monthly period. Less is known about how unmarried young women living in low-income urban areas in India seek help for their menstrual needs. This qualitative study seeks to understand how young unmarried women (aged 15–24) living in a slum settlement understand menstruation and perceive menstrual problems, and identifies factors that influence their help-seeking behaviour for menstrual needs and problems. It also proposes recommendations for national health programmes addressing menstrual health and hygiene.

The findings echo previous research findings emphasising young unmarried women’s low levels of awareness and misconceptions about menstruation. These girls perceived menstrual problems as a key concern, as it significantly interfered with their daily routine and caused emotional distress. Young women’s ability and willingness to seek help to address menstrual needs is influenced by a culture of silence that surrounds menstruation, excessive scrutiny and blaming by the community, and restrictions on their mobility and interactions with peers. The findings underscore the role of mothers as gatekeepers who greatly influence young women’s perceptions of menstruation and menstrual problems and their ability to seek help.

Existing interventions need to be expanded to address young women’s need for emotional and social support, and to involve significant gatekeepers such as mothers in promoting the health and well-being of young unmarried women in slum communities. Intervention strategies should be expanded to enhance the capacity of mothers to recognise, understand and address their teenage daughters’ needs for information, emotional support and access to essential clinical and social services.

Early Puberty, School Context, and Delinquency Among South Korean Girls

Compared with chronological age, criminologists have paid less attention to the biological sense of age typically expressed by pubertal development. Studies that have examined pubertal timing's effects on delinquency have almost exclusively been conducted in Western countries using mostly White samples. To our knowledge, no study has ever examined this issue in the Asian context. The current study is the first attempt to bridge this research gap by examining the association among menarcheal timing, the sex composition of schools, and delinquency in a representative sample of 1,108 ninth-grade girls in South Korea. The results show that significant association between early menarche and delinquency exists only in mixed-sex schools but not in all-girls schools. In addition, the significant linkage between early menarche and delinquency in mixed-sex schools is mediated by delinquent peer associations.

What does the mean menarcheal age mean?-An analysis of temporal pattern in variability in a historical swiss population from the 19th and 20th centuries

OBJECTIVES

Age at menarche is one of the most important factors when observing growth and development. The aim of this study was to assess the temporal pattern in variability of menarcheal age for a historic Swiss population from the 19th and 20th centuries.

METHODS

Medical health records from the Bernese women's hospital (Switzerland) were analyzed. From 10,081 women of a historical Swiss population (born from 1815 to 1954), menarcheal age was calculated. A possible decline in average menarcheal age and variance and skewness were analyzed with the use of descriptive statistics, generalized additive models, and correlation.

RESULTS

Mean menarcheal age declined from 17.34 years (n = 358) around 1830 to 13.80 years (n = 141) around 1950. Within-cohort variance decreased from 7.5 to 2.1 year(2) . Skewness was negatively correlated with birth year (r = -0.58).

CONCLUSION

This study provided evidence for a secular trend in various statistical parameters for age at menarche since the 19th century. Furthermore, the results of the analysis of temporal pattern in variability revealed that the secular trend in menarcheal age happened in two phases. Am. J. Hum. Biol. 28:705-713, 2016. © 2016 Wiley Periodicals, Inc.

Psychosocial and Cultural Factors Influencing Expectations of Menarche

This study explored how psychosocial and cultural factors influenced expectations of menarche among 476 Chinese premenarcheal teenage girls. Results showed that participants’ expectations of menarche were largely negative and heavily influenced by cultural beliefs about menstruation. Findings of hierarchical regression analyses revealed that positive emotional expectations of menarche were best predicted by perceptions of menstruation as a natural event, possession of positive self-concept, and rejection of indigenous negative menstrual attitudes. Negative emotional expectations of menarche were best predicted by perceptions of menstruation as a negative event, by inadequate preparation for menarche, by endorsement of indigenous negative menstrual attitudes, and by older age.

The influence of climate on age at menarche: Augmented with the influence of ancestry

Samples representative of South Korea, Indonesia, and Peninsular Malaysia were analyzed and the influence of climate on age at menarche was investigated. The sample size was 24,651 for Korea (birth years 1941-1992), for Indonesia 8331 (birth years 1944-1988) plus 20,519 (birth years 1978-1997), and 2842 for Peninsular Malaysia (birth years 1927-1968). Respondents recalled their age at menarche. The mean age at menarche was calculated for each birth year by country, and for Malaysia, additionally by ancestry. It has been found that mean ages at menarche for the early birth years were much younger in Indonesia than in Korea despite similar levels of socioeconomic conditions (proxied by GDP per capita). For example, for the birth year 1944, the mean age at menarche was 14.45 years for Indonesia and 16.19 years for Korea-a difference of 1.74 years. It was necessary to double the Korean GDP per capita to make the Korean mean age at menarche the same as the Indonesian one. Chinese and Malay women in Peninsular Malaysia were further analyzed, and the results provided indirect evidence that the difference between Korea and Indonesia was not due to ancestry differences. Results in multivariate settings provided consistent results. It has been concluded that climate exerts a significant influence on age at menarche because the relatively easy availability of food in the tropics increases energy intake while the absence of cold weather decreases energy expenditure on maintenance and activity.

Improvement in the biological standard of living in 20th century Korea: Evidence from age at menarche

OBJECTIVES

We used age at menarche to understand improvement in the biological standard of living in South Korea during the 20th century.

METHODS

The main dataset, the Korean National Health and Nutrition Examination Survey, provided a consistent source of nationally representative data with a large number of observations over a long period of time. We calculated mean ages at menarche by birth year and estimated the rate of decrease in age at menarche, while avoiding survival bias.

RESULTS

The mean age at menarche decreased from 16.64 for the birth year 1941 to 12.68 for the birth year 1992, decreasing 0.78 (or 0.81 in a regression) years per decade for the period. Comparisons with other populations demonstrate that this is the fastest rate of decline ever known. In contrast to other developed countries, the decreasing rate in Korea does not appear to slow. We also compared the trend in age at menarche to that of height and found that the rate of increase in height is also the fastest in history.

CONCLUSIONS

Age at menarche is an appropriate index of change in the general standard of living in South Korea over the 20th century. Am. J. Hum. Biol. 29:e22882, 2017. © 2016 Wiley Periodicals, Inc.

Pattern of teen menstruation among secondary school girls in south east Nigeria

BACKGROUND

Menstruation in the teenage age has assumed variable trends which is been influenced by several variables. This study is aimed at determining the pattern and trend of menstruation among teens attending secondary school in south east Nigeria and associated factors.

METHODS

Menstruation patterns were investigated using a stratified random sampling method of teens from junior secondary schools in Enugu, south east Nigeria. A self-administered questionnaire was developed and data analyzed using SPSS version 19.

RESULTS

A total of 897 female teenagers aged 9-18 years completed the questionnaire with a mean age of 13.9±1.9 years. The mean age (SD) at onset of menarche was 12.5±1.2 years. Teenage girls with higher BMI achieved menarche earlier at age 8 and 9 when compared with their counterparts with lower BMI and this is statistically significant. F=7.60, df=8, p<0.001. Teens with a 14-day cycle had a higher BMI when compared with teens with longer cycle but this is not statistically significant. F=1.05, df=4, p=0.381. There is a statistical significance difference between teens duration of menstrual flow and BMI. Those with higher BMI had longer duration(4-5 days) compared with those with lower BMI. F=3.329, df=4, p=0.01 CONCLUSIONS: This study revealed that the mean age at onset of menarche was 12.5±1.2 years showing a continuing decreasing trend. Teens with higher BMI attain menarche earlier and had longer days of periods when compared with their counterpart with lower BMI.

The trend in age at menarche in Indonesia: birth cohorts 1944–1988

Employing the Indonesian Family Life Survey, this paper depicts the trend in age at menarche in Indonesia for women born in 1944–1988. Mean age at menarche decreased from 14.39 years for birth year 1944 to 13.18 years for birth year 1988. Subsequently, this trend is related to the improvement in material conditions, measured by GDP per capita in childhood. The OLS results indicate that this decrease is largely explained by the improvement in material conditions. If age at menarche is considered an indicator of biological standard of living, these results suggest that the improvement in material conditions during the period converted to an improvement in biological standard of living.

Age at menarche and its association with dysglycemia in Korean middle-aged women

Objective

Recent studies have demonstrated that earlier menarche is associated with increased risks of prediabetes and diabetes in white women; however, the associations have not been fully explored in Asian populations. We investigated the associations between age at menarche and prediabetes and/or diabetes in Korean middle-aged women.

Methods

This was a cross-sectional study of 2,039 premenopausal and postmenopausal women aged 44 to 56 years who visited the health promotion center for medical checkups. Participants were divided into three groups based on age at menarche: early (<13 y), average (13-16 y), and late (>16 y).

Results

The mean (SD) age at menarche was 14.6 (1.6) years. Of 2,039 women, 820 and 85 women had prediabetes (impaired fasting glucose and/or 5.7%-6.4% glycated hemoglobin) and diabetes, respectively. On logistic regression analysis, earlier menarche was significantly associated with prediabetes (odds ratio [OR], 1.80; 95% CI, 1.24-2.61; P = 0.002), diabetes (OR, 2.43; 95% CI, 1.04-5.69; P = 0.04), and dysglycemia (OR, 1.85; 95% CI, 1.28-2.66; P = 0.001), after adjusting for a number of confounding factors, compared with average age at menarche. On linear regression analysis, earlier age at menarche was significantly associated with increased fasting insulin, homeostatic model assessment for insulin resistance, homeostatic model assessment for β-cell function, body mass index, and waist circumference.

Conclusions

Age at menarche is inversely associated with various forms of dysglycemia. A history of earlier menarche may be helpful in predicting prediabetes and subsequent diabetes in Korean women.

Secular trends in age at menarche among women born between 1955 and 1985 in Southeastern China

Background

Improvements in socioeconomic conditions and population health have been linked to declining age at menarche. In China, secular trends in age at menarche following extensive economic reform during recent decades have not been thoroughly investigated. This study examined the overall trend in age at menarche and assessed differences in the rate of change of age at menarche over time, and between urban and rural populations and education levels in southeastern China.

Methods

Age at menarche was retrospectively collected from 1,167,119 Han Chinese women born 1955–1985, who registered in the Perinatal Health Care Surveillance System in 19 cities and counties in two southeast provinces during 1993–2005. Multivariable linear regression was used to estimate trends in age at menarche overall and stratified by urban/rural residence and education level.

Results

Age at menarche declined by 0.33 [95% CI 0.33, 0.32] years/decade overall, with the fastest decline in women born in 1966–1975. For the earliest birth cohorts (1955–1965), age at menarche declined faster in urban versus rural regions, and for women with high school education or above versus primary school or less. In contrast, age at menarche declined slower among urban women born 1976–1985, and among those with higher education born 1966–1985.

Conclusions

Mean age at menarche declined for women born in 1955–1985 in southeast China. Further study is warranted to identify specific factors contributing to earlier age at menarche and associated health outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12905-014-0155-0) contains supplementary material, which is available to authorized users.

Age at menarche in a group of French schoolgirls

BACKGROUND

Mean age at menarche in France decreased from 12.78 years in 1979 to 12.6 years in 1994. The aim of this study was to determine mean age at first menstruation in French adolescent girls in order to study the secular trend.

METHODS

Age at first menstruation was noted to the nearest month during recording of anthropometric measurements in three secondary schools in the Aisne administrative department, France, in classes in years 7, 8, 9 and 10. A total of 339 girls aged 11-15 ½ years were examined. The majority were from a social background of workers, employees and middle managerial staff. Mean age at first menses and standard deviation were calculated using the probits method.

RESULTS

Mean age was 12.5 ± 0.08 years (χ(2) γ=14 = 16.7, P > 0.05), indicating that it had remained stable for more than 15 years.

CONCLUSIONS

A secular decline has already been observed in Belgium, Britain, Hungary, Scandinavia and the USA. In all these countries, age at menarche has reached a stable level at around 13 ± 0.5 years.

Relationships between biomarkers of inflammation, ovarian steroids, and age at menarche in a rural Polish sample

OBJECTIVES

To test the hypothesis that life history trade-offs between maintenance and reproductive effort would be evident through inverse associations between levels of a biomarker of inflammation [C-reactive protein (CRP)], and ovarian hormones. Associations between CRP and age at menarche were also explored.

METHODS

Urinary CRP, salivary progesterone, and estradiol were measured over one menstrual cycle from rural Polish women (n = 25), representing a natural fertility sample. Age of menarche was assessed through interview recall methods. We used minimum second-order Akaike Information Criteria as a means of multiple regression model selection, and repeated measures ANOVA to test cycle-dependent hypotheses.

RESULTS

Comparisons of individuals in high and low CRP tertiles revealed that those with high CRP had significantly lower progesterone (luteal P = 0.03, mid luteal P = 0.007) but not estradiol (follicular P = 0.21, luteal P = 0.15) concentrations through the menstrual cycle. However, when the age at menarche was included in the analysis, both age at menarche and urinary CRP were negatively associated with estradiol (R(2) = 0.44, P = 0.0007). Age at menarche and estradiol were the strongest negative predictors of CRP (R(2) = 0.52, P = 0.0001).

CONCLUSIONS

Inflammation itself may suppress ovarian function, or indicate immune challenges that lead to ovarian suppression. The timing of menarche may also influence adult inflammatory sensitivity and ovarian hormone concentrations. This lends support to existing models of trade-offs between maintenance and reproduction in women.

Age at menarche in the Korean female: secular trends and relationship to adulthood body mass index

PURPOSE

The objective of this study is to estimate the trend in age at menarche in the Korean female and evaluate the relationship between age at menarche and adult body mass index (BMI), which is a indicator of later-life health.

METHODS

We conducted a cross-sectional analysis of a nationally representative sample (self-reported age at menarche and measured height and weight) of 11,065 females aged 15 and older. Data were obtained from the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV, 2007-2009).

RESULTS

We found a statistically significant decline in age at menarche in successive birth groups, indicating a 0.726 year decrease per decade. The age at menarche in 1990-1994 year birth group was 12.60 years, which showed a significant decreased from 3.11 years in the 1980-1984 birth group. We also found a significant negative association between age at menarche and current BMI. A one-year decrease in age at menarche was associated with mean BMI increase of 0.109 kg/m(2) (95% confidence interval [CI], 0.069 to 0.150) after adjustment for age. In multivariate logistic regression, the odds ratios of obesity in females with early menarche (<12 years) was 1.845 fold (95% CI, 1.441 to 2.361).

CONCLUSION

We found that age at menarche is still falling in the Korean female. We also found that early menarche is a risk factor for obesity in adults.

Evaluation of GWAS-identified genetic variants for age at menarche among Chinese women

STUDY QUESTION

Do genetic polymorphisms which influence age at menarche in women of European ancestry also influence women of Chinese ancestry?

SUMMARY ANSWER

Many genetic variants influencing age at menarche in European populations appear to impact Chinese populations in a similar manner.

WHAT IS KNOWN AND WHAT THIS PAPER ADDS

Prior genome-wide association studies have uncovered 42 SNPs associated with age at menarche in European populations. This study is the first to demonstrate that many of the genetic determinants of age at menarche are shared between European and Chinese women.

PARTICIPANTS AND SETTING

We evaluated 37 of 42 SNPs identified as associated with age at menarche from a recent, large meta-analysis, consisting primarily of women of European ancestry, in a population of 6929 Chinese women from Shanghai, China. We also constructed weighted genetic risk scores (GRSs) combining the number of effect variants for all 37 SNPs, or only the SNPs associated with age at menarche among our study population, to evaluate their joint influence on age at menarche.

MAIN RESULTS

For 32 of the 37 evaluated variants, the direction of the allele associations were the same between women of European ancestry and women of Chinese ancestry (P = 3.71 × 10(-6), binomial sign test); 9 of these were statistically significant. Subjects in the highest quintile of GRSs began menarche ∼5 months later than those in the lowest quintile. BIAS, LIMITATIONS AND GENERALIZABILITY TO OTHER POPULATIONS: Age at menarche was obtained by self-report, which can be subject to recall errors. The current analysis was restricted to loci which met or approached GWAS significance thresholds and did not evaluate loci which may act predominantly or exclusively in the Chinese population. The smaller sample size for our meta-analysis compared with meta-analyses conducted in European populations reduced the power to detect significant results.

STUDY FUNDING/COMPETING INTERESTS

This study was supported, in part, by grants from US National Institutes of Health (grants R01CA124558, R01CA090899, R01CA070867; R01CA064277 and R01CA092585 and UL1 RR024975), Ingram professorship funds and Allen Foundation funds. There are no competing interests to declare.

Association of age at menarche with metabolic syndrome and its components in rural Bangladeshi women

BACKGROUND

Early age at menarche is associated with increased risk of metabolic syndrome in both China and the West. However, little is known about the impact of age at menarche and metabolic syndrome in South Asian women, including those from low-income country, where age at menarche is also falling. The aim of the present study was to investigate whether age at menarche is inversely associated with metabolic syndrome in Bangladeshi women, who are mostly poor and have limited access to and or poor health care facilities.

METHODS

This community-based cross-sectional study was performed using 1423 women aged between 15-75 years from rural Bangladesh in 2009 and 2010. Metabolic syndrome was defined according to standard NCEP-ATP III criteria. Logistic regression was used to estimate the association between age at menarche and metabolic syndrome, with adjustment of potential confounding variables, including age, education, marital status, tobacco users, use of contraceptives and number of pregnancies.

RESULTS

Early onset of menarche (<12 years) as compared to late onset (>13 years) was found to be associated with a higher prevalence of metabolic syndrome (odds ratio=1.55; 95 % confidence interval =1.05-2.30). Age at onset of menarche was also inversely associated with prevalence of high triglycerides (P for trend <0.01) and low high-density lipoprotein cholesterol (P for trend = 0.01), but positively associated with prevalence of high fasting blood glucose (P for trend =0.02). However, no significant association was found between age at menarche, high blood pressure and elevated waist circumference.

CONCLUSION

Early onset of menarche might promote or trigger development of metabolic syndrome. Thus, knowledge of the history of age at onset of menarche may be critical in identifying women at risk of developing metabolic syndrome and those likely to benefit the most from early interventions.

Breast cancer incidence in Mongolia

PURPOSE

Data on international variation in breast cancer incidence may help to identify additional risk factors. Substantially lower breast cancer rates in Asia than in North America and Western Europe are established, but differences within Asia have been largely ignored despite heterogeneity in lifestyles and environments. Mongolia's breast cancer experience is of interest because of its shared genetics but vastly different diet compared with other parts of Asia.

METHODS

Age-standardized breast cancer incidence and mortality rates obtained from the International Association of Cancer Registries are presented for several Asian countries. Mongolian incidence rates obtained from its cancer registry describe incidence within the country.

RESULTS

Breast cancer incidence in Mongolia (age standardized 8.0/100,000) is almost a third of rates in China (21.6/100,000), and over five times that of Japan (42.7/100,000) and Russia (43.2/100,000). Rates within Mongolia appear to have increased slightly over the last decade and are higher in urban than rural areas (annual percentage increase of age-standardized rates from 1998 to 2005 was 3.60 and 2.57 %, respectively). The increase in breast cancer incidence with age plateaus at menopause, as in other Asian populations.

CONCLUSIONS

Mongolia's low breast cancer incidence is of particular interest because of their unusual diet (primarily red meat and dairy) compared with other Asian countries. More intensive study of potential dietary, reproductive and lifestyle factors in Mongolia with comparison to other Asian populations may provide more clarity in what drives the international breast cancer rate differences.

Genetics of age at menarche: a systematic review

BACKGROUND

Menarche is the first menstrual period of a girl at puberty. The timing of menarche is important for health in later life. Age at menarche is a complex trait and has a strong genetic component. This review summarizes the results of the genetic studies of age at menarche conducted to date, highlights existing problems in this area and outlines prospects of future studies on genetic factors for the trait.

METHODS

PubMed and Google Scholar were searched until May 2011 using the keywords: 'menarche', 'puberty' and 'age at menarche' in combination with the keywords 'polymorphism', 'candidate gene', 'genome-wide association study' and 'linkage'.

RESULTS

Our search yielded 170 papers, 35 of which were selected for further analysis. Several large-scale genome-wide association studies along with a powerful meta-analysis of their aggregated data identified about 50 candidate genes for the trait. Some genes were replicated in different studies of Caucasians (e.g. LIN28B, TMEM38B) or in different ethnicities (e.g. SPOCK, RANK and RANKL). However, despite the large volume of results obtained, there is a huge gap in relevant data on ethnic groups other than Caucasians.

CONCLUSIONS

The reviewed studies laid a solid basis for future research on genetics of age at menarche. However, as yet specific genes for this trait have not been identified consistently in all ethnicities and types of studies. We suggest expanding the research to different ethnicities and propose several methodologies to increase the efficiency of studies in this area, including a systems approach, which combines existing high-throughput methods in a single pipeline.

Risk factors for breast cancer: a reanalysis of two case-control studies from 1926 and 1931. Epidemiology. 2010;21:566-572. [PMID: 20498604 DOI: 10.1097/ede.0b013e3181e08eb3]

BACKGROUND

The first major case-control study, published by Janet Lane-Claypon in 1926, provided the first epidemiologic evidence that low fertility increases breast cancer risk. This study in the United Kingdom was replicated in 1931 by JM Wainwright using a US sample. Neither study used modern statistical inference to interpret their data. We have evaluated and reanalyzed data from both studies to assess the validity of the original conclusions about the etiology of breast cancer.

METHODS

We abstracted data from the published contingency tables for age at menarche, age at menopause, parity, age at marriage (as a proxy for age at first birth), and duration of lactation for each childbirth (as a proxy for lifetime duration of lactation). Study-specific odds ratios and associated 95% confidence intervals were calculated.

RESULTS

Findings from the quantitative reanalysis were consistent with contemporary epidemiologic evidence for age at menopause, parity, age at first birth, and duration of lactation.

CONCLUSIONS

Lane-Claypon's scientific efforts, as manifested in the 1926 UK study, are an excellent example of how one investigator's work can help develop a field of scientific inquiry.

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.

Age at menarche in a Korean population: secular trends and influencing factors

This study was designed to identify the secular trend in the age at menarche and to investigate the possible factors that influence the age at menarche using representative Korean data from the 2005 Korean National Health and Nutrition Survey. Three thousand five hundred sixty-two women born between 1920 and 1985 were enrolled to identify secular trends in the age at menarche and 620 girls born between 1986 and 1995 were recruited to evaluate the factors influencing the age at onset of menarche. Mean age at menarche decreased from 16.90 +/- 1.25 years for women born between 1920 and 1925 to 13.79 +/- 1.37 years for those born between 1980 and 1985, indicating a downward trend of 0.68 years per decade (95% CI, 0.64-0.71) in age at menarche. Mean age at menarche of girls born between 1986 and 1995 was 13.10 +/- 0.06 years as estimated by the Kaplan-Meier method. Among girls born between 1986 and 1995, menarcheal girls had a larger waist circumference, a higher body mass index (BMI), and lower maternal menarcheal age and maternal age at birth than premenarcheal girls. The energy and nutrient intake of protein, sugar, fiber, ash, phosphate, natrium, thiamine, riboflavin, and niacin were greater for menarcheal girls than for premenarcheal girls. These data indicate a decreasing secular trend of age at menarche in a Korean population born between 1920 and 1995. Furthermore, maternal menarcheal age, BMI, maternal age at birth, and nutrition are important variables that appear to influence age at menarche in Korean girls.

Perceptions of adolescents and their mothers on reproductive and sexual development in Matlab, Bangladesh

Adolescence is the stepping stone for a child to reach adulthood. Although generally delimited by age, this stage is primarily a social and cultural classification based on markers of development, such as menarche (the first menstruation of girls) and spermarche (indicated by the first self-reported ejaculation of boys as proximity).

OBJECTIVE

Aim of this study was to investigate the perceptions of adolescents and their mothers on markers of reproductive and sexual development.

STUDY GROUP

The study was conducted among 12 to 16-year-old adolescent girls and boys, in Matlab, Bangladesh. Their mothers were also interviewed.

METHODS

Data were collected by means of a survey and through in-depth interviews.

RESULTS

The study revealed that adolescent girls and boys are not adequately informed about menarche and spermarche, indicating a less than optimal mental wellbeing in reproductive life. No less than 64% of the adolescent girls reached menarche in fear. The lack of knowledge about the origins of menstruation seems to be an intergenerational problem as the mothers lacked adequate information as well.

CONCLUSIONS

This paper argues that having an understanding of reproductive development is a prerequisite to being able to make contemporary and future informed choice(s). In Bangladesh, mental well-being in reproductive life is a dimension that is easily overshadowed by the physical aspects of reproductive health. Sexual education for adolescent girls and boys must be programmed urgently, to improve not only their own sexual and reproductive health status but also that of future generations.

Height, its components, and cardiovascular risk among older Chinese: a cross-sectional analysis of the Guangzhou Biobank Cohort Study

OBJECTIVES

Better childhood conditions, inferred from height and specifically leg length, are usually protective against ischemic heart disease and its risk factors in Western countries. In other geoethnic populations, height is less clearly protective, casting doubt on there being a biological etiology. To clarify the role of childhood conditions, we examined the associations of height and its components with cardiovascular risk among older Chinese people.

METHODS

We used multivariable regression to examine the associations of height and its components with blood pressure, lipid profile, and diabetes in 10413 older Chinese adults (mean age=64.6 years).

RESULTS

After we adjusted for age, gender, socioeconomic status, and lifestyle habits, greater sitting height was associated with diabetes and dyslipidemia. Longer legs were associated with lower pulse pressure and lower low-density lipoprotein cholesterol.

CONCLUSIONS

We provide indirect anthropometric evidence for the role of pre-pubertal and pubertal exposures on cardiovascular risk. Pubertal exposures are stronger than are prepubertal exposures but may be influenced by osteoporotic decline in old age. Further research should establish whether the observed relations are ethnically specific or relate to the stage or trajectory of socioeconomic development.

Long-term growth and puberty concerns in international adoptees

Growth delay is one of the most common and persistent findings in children who have been adopted from abroad. Although the cause is not clearly understood, it may be related to the observed phenomenon of psychosocial short stature described in children from abusive and neglectful settings in western countries. Fortunately, adopted children generally experience significant improvement in growth after joining their new family, but this may put girls at risk for early and rapidly progressing puberty. This review should help the health care team to understand these issues and work better with the adoptive parents to ensure a child's smooth transition into family life.

Secular trends in age at menarche among Caboclo populations from Pará, Amazonia, Brazil: 1930-1980

The present study is part of a large research project on growth, development, nutrition, and health of Caboclo populations from the Brazilian Amazon. The aim of this paper is to analyze the age of menarche in adolescents (N=164) and adult women (219) in the studied populations. Caboclo are admixed rural, peasant groups that live along the Amazon river and its tributaries, and there are few previous studies about them. Probit analysis of the status quo data yielded a median age at menarche of 12.29+/-1.76 years. The retrospective method was applied to recall data of the 77 post-menarcheal adolescents, yielding an average of 13.06+/-1.27 years. Number of children in the family did not show any statistical influence on age at menarche in any age group. In adult women, age at menarche decreased from 14.50 in those born in 1930 to 12.88 for those born in 1980 (F=4.371, P=0.001). The downward trend found was, on average, 0.237 year per decade in the study period. The median age at menarche in the adolescents (12.29 years) is one of the lowest values found for Central and South American populations. In the ecological context, a low age at menarche could be an adaptive advantage because it provides a greater chance for reproduction at a young age in an environment where, until recently, life expectancy was low. As has been reported for other developing countries, the change found in age at menarche in the women born from the 1930s to the 1980s is likely to be related to changes in health and nutritional factors that occurred in Brazil because this country experienced significant improvement in living standards related to education, vaccination, and health conditions, which, although not equally, reached all regions after the 1960s.

Age at menarche and age of onset of pubertal characteristics in 6-14-year-old girls from the Province of L'Aquila (Abruzzo, Italy)

The present study is part of a research project on growth models of children in an area of central-southern Italy. It analyzes the phases of pubertal breast development (BD) in 397 girls, pubic hair development (PHD) in 399 girls, and menarche in 583 girls from 6-14 years old. The status quo method was used to evaluate the age at menarche. Probit analysis was used to analyze the data for all three variables. The onset of BD and PHD (Tanner stage 2) occurs at age 7 in 6.1% of girls. Passage to stage 3 of one or both secondary sexual characteristics occurs at age 10 in 8.5% of girls. Comparison with data from the United States shows higher percentages of American white girls in stage 2 (or greater) of both characteristics at any age. The mean (median) age of onset (Tanner stage 2) of BD or PHD or both of them is 9.96 years. The passage to stage 3 occurs at age 12.36 for BD (95% confidence interval: 1.36 years) and at age 12.10 for PHD (95% confidence interval: 0.51 years). The mean age at menarche is 12.55 years, in general agreement with other values found in Italy. Sexual maturation at any considered stage for both pubertal characteristics is generally in line with literature data concerning other Mediterranean and industrialized countries or countries in which the demographic transition is in an advanced phase. It does not show a significant earlier onset. The evidence emerging from the general project suggests that the secular trend is still in progress in this region of Italy.

Recent decline in age at menarche: The Fels Longitudinal Study

A number of recent reports suggest that the average age at menarche of US girls has declined over the past 20 years. Because the putative declines in the age at menarche are concurrent with increases in childhood body mass index (BMI), it has been suggested that these two trends may be causally linked. We examined differences in mean age of menarche in Fels Longitudinal Study girls who were born in six 10-year birth cohorts (1930s, 1940s, 1950s, 1960s, 1970s, and 1980s) and simultaneous cohort changes in mean BMI measured cross-sectionally at selected ages from 3-35 years (n = 371). Girls born in the 1980s had a mean age at menarche of 12.34 years, which was approximately 3-6 months earlier than that of girls born previously (P < 0.001). While the mean BMI values at ages 25 and 35 generally increased from the 1930s to the 1970s, the mean BMI during childhood and adolescence remained constant across the six birth cohorts. In summary, we found no evidence that the recent decline in the age at menarche in the Fels Longitudinal Study girls was reflected in concurrent increases in BMI at any point in childhood or adolescence. Conversely, girls born in the 1960s and 1970s have subsequently become heavier in young and mid-adulthood than were girls from earlier birth cohorts, without any concurrent change in the mean age at menarche over that time period. These two findings suggest that population-level shifts in BMI and the timing of menarche are largely independent, although sometimes coincident, processes.

The timing of normal puberty and the age limits of sexual precocity: variations around the world, secular trends, and changes after migration

During the past decade, possible advancement in timing of puberty has been reported in the United States. In addition, early pubertal development and an increased incidence of sexual precocity have been noticed in children, primarily girls, migrating for foreign adoption in several Western European countries. These observations are raising the issues of current differences and secular trends in timing of puberty in relation to ethnic, geographical, and socioeconomic background. None of these factors provide an unequivocal explanation for the earlier onset of puberty seen in the United States. In the formerly deprived migrating children, refeeding and catch-up growth may prime maturation. However, precocious puberty is seen also in some nondeprived migrating children. Attention has been paid to the changing milieu after migration, and recently, the possible role of endocrine- disrupting chemicals from the environment has been considered. These observations urge further study of the onset of puberty as a possible sensitive and early marker of the interactions between environmental conditions and genetic susceptibility that can influence physiological and pathological processes.

Psychosocial correlates of emotional responses to menarche among Chinese adolescent girls

PURPOSE

To determine the psychosocial correlates of emotional responses to menarche among Chinese adolescent girls.

METHODS

A large sample of 1573 post-menarcheal Chinese junior high school students in Hong Kong completed questionnaires on knowledge and preparation of menarche, attitudes toward menstruation, gender-role attitudes, body image, self-esteem, and emotional responses to the onset of the first menstruation. Pearson correlation and hierarchical regression analyses were conducted to determine associations among variables.

RESULTS

Participants' mean age at menarche was 11.67 years. Their emotional reactions to menarche were largely negative, with almost 85% reporting feeling annoyed and embarrassed. In spite of these negative feelings, about two-thirds of the participants also reported feeling grown up and another 40% felt as if becoming more feminine. Results of the hierarchical regression analyses showed that negative emotional responses to menarche were correlated with perceptions of menstruation as a negative event, inadequate preparation for menarche, endorsement of indigenous negative menstrual attitudes, and poor self-esteem (24.5% variance explained). Positive emotional responses to menarche were correlated with perceptions of menstruation as a natural event, rejection of indigenous negative menstrual attitudes, positive body image, and adequate preparation for menarche (13.4% variance explained).

CONCLUSIONS

This study illustrates the need to attend to various psychosocial and cultural factors in the understanding of Chinese adolescent girls' responses to their first menstruation. In particular, general and indigenous menstrual attitudes, which may have been internalized by Chinese adolescent girls at an early age, are found to be the most salient correlates of their emotional responses to menarche.

Age at menarche in Coimbra (Portugal) school girls: a note on the secular changes

The age at menarche and several menstrual symptoms were reported by 516 Portuguese school girls who took part in a cross-sectional anthropometric study in Coimbra, Portugal. The mean ages of menarche calculated using the recall method and also using probit analysis were 12.53 +/-1.27 and 12.03 +/- 1.26 years, respectively. Parents'educational level, place of residence and size of the family did not have any significant effect on the mean age at menarche in this sample of adolescents. The order of birth was the only variable that indicated a significative effect: the first borns reported a lower mean age at menarche (12.34 years) than the later borns (12.6 years). In this sample, 47% of the girls had a cycle length of >or = 29 days, 23.4% had irregular cycles, 59% reported that the duration of bleeding was 3-5 days and the majority, 49%, did not report any pain during the bleeding days. However, 14.3% and 24.45% reported severe and medium pain. The age at menarche has declined from 15.0 (girls born in 1880-1890) to 12.03 (girls born in 1970-1980) years in the Portuguese population. This decrease in age, and also the lack of influence of the family characteristics, appear as a result of the great improvements in the social and economic living conditions that occurred in Portugal, especially after the 1970s. These improvements are mainly related to better nutrition and better health care along with many other environmental factors.

A low-fat, whole-food vegan diet, as well as other strategies that down-regulate IGF-I activity, may slow the human aging process

A considerable amount of evidence is consistent with the proposition that systemic IGF-I activity acts as pacesetter in the aging process. A reduction in IGF-I activity is the common characteristic of rodents whose maximal lifespan has been increased by a wide range of genetic or dietary measures, including caloric restriction. The lifespans of breeds of dogs and strains of rats tend to be inversely proportional to their mature weight and IGF-I levels. The link between IGF-I and aging appears to be evolutionarily conserved; in worms and flies, lifespan is increased by reduction-of-function mutations in signaling intermediates homologous to those which mediate insulin/IGF-I activity in mammals. The fact that an increase in IGF-I activity plays a key role in the induction of sexual maturity, is consistent with a broader role for-IGF-I in aging regulation. If down-regulation of IGF-I activity could indeed slow aging in humans, a range of practical measures for achieving this may be at hand. These include a low-fat, whole-food, vegan diet, exercise training, soluble fiber, insulin sensitizers, appetite suppressants, and agents such as flax lignans, oral estrogen, or tamoxifen that decrease hepatic synthesis of IGF-I. Many of these measures would also be expected to decrease risk for common age-related diseases. Regimens combining several of these approaches might have a sufficient impact on IGF-I activity to achieve a useful retardation of the aging process. However, in light of the fact that IGF-I promotes endothelial production of nitric oxide and may be of especial importance to cerebrovascular health, additional measures for stroke prevention-most notably salt restriction-may be advisable when attempting to down-regulate IGF-I activity as a pro-longevity strategy.

Social background and age at menarche in Portuguese university students: a note on the secular changes in Portugal

Menarcheal age of a sample of Portuguese university students (n = 3366), born between 1972 and 1983, age 18-23 years, was analyzed. The influence of parents' educational level and occupation, family size, birth order, and degree of urbanization of girl's locality of residence during childhood and adolescence were analyzed as well as secular trend in the Portuguese population. Mean age at menarche for girls born in 1983 was 12.32 years. Parents' educational level and occupation did not show any significant influence on mean age at menarche. Place of residence during childhood years and adolescence showed a significant effect on mean age at menarche, with girls from rural places with a later age at menarche than those who spent their childhood or adolescence in urban areas (P <or= 0.01 and P <or= 0.05 for childhood and adolescence, respectively). Family size and birth order showed the highest effect. Girls born in small families, with one child, matured earlier (12.32 years) than those born in large families with four or more children (12.67 years), (P <or= 0.01). Also, girls that were first-born had an earlier menarche (12.41 years) than those who were third or later (12.58 years, P <or= 0.01). Regression analysis selected family size and place of residence in childhood as the most important determinants of mean age at menarche in our university students. In this sample, from 1972 to 1983, mean age at menarche remained stable. When we considered published data from all the Portuguese population we found a decrease in mean age at menarche from 15 years for girls born in 1880 to 12.44 for those born in the 1980s. This decrease was the result of great improvements in the social and economic living conditions that occurred in Portugal especially after the 1970s concerning nutrition and health care, among many other environmental factors.

Early puberty in adopted children

Early puberty is frequently observed in adopted children. In various studies, early puberty has been associated with decreased final height. In Europe, studies were undertaken to treat early puberty in adopted children with GnRH agonist. This article reviews the current understanding of early puberty in adopted children, including prevalence, background and treatment options. Data from the European studies are briefly described. Besides auxological aspects, psychological items are addressed as well. Studies on the psychological effect of early puberty in adopted children are reported. Future issues include further study in the mechanism of early puberty in adopted children, evaluation of final height results of the growth studies and quality of life assessments in this specific group of children.

Evolution of age at menarche and at onset of regular cycling in a large cohort of French women

BACKGROUND

Early exposure to ovarian hormones is considered to increase breast cancer incidence. The age at which the ovaries become functional is thus important.

METHODS

We explored the evolution of age at first menstruation and at onset of regular cycling in 86 031 women participating in the E3N-EPIC cohort study, part of the European Prospective Investigation into Cancer.

RESULTS

We observed an increase in mean age at menarche among women born between 1925 and 1930, followed by a steady decrease in the youngest birth cohorts. In contrast, age at onset of regular cycling increased gradually from 1925 onwards. There was thus a steady increase in the interval between age at menarche and at onset of regular cycling, mainly due to an increase in the percentage of women in whom regular cycling started at least 5 years after menarche (from 9.0% among women born in 1925-1929 to 20.8% in those born in 1945-1950). The increase in the interval between menarche and onset of regular cycling was even greater among women with a late menarche.

CONCLUSIONS

This increase might be due to a change in dietary intake and/or physical exercise aimed at achieving the slim silhouette desired by the younger generations.

Secular trend in tooth size in urban Chinese assessed from two-generation family data

Environmental improvements can lead to greater size of skeletodental structures as the population comes closer to expressing its genetic growth potential. Such secular trends have been documented in many human settings, especially for increased stature and faster tempos of growth. The present study is based on 185 same-sex parent-offspring pairs of data for maximum buccolingual crown diameters of the permanent teeth from a cohort in Beijing, China, where parents experienced much of their development during and after World War II with the deprivations of the changing regime. Their offspring enjoyed the relative stability of the established Communist system, where nutrition and stability were much improved. There were significant increases in buccolingual diameters of the premolars and molars in the offspring. Increase for premolars and molars was about 1%, but larger in females than males (1.6% vs. 0.5%). Opposite changes occurred in the incisors and canines (i.e., larger parental dimensions), but we contend that these are an age-related artifact brought on by greater passive eruption of older individuals' teeth that exposes a broader portion of the crown at the gingival margin. The secular trend in crown size coincides with other research in contemporary China, disclosing increases in body size and faster tempos of growth as health and nutrition continue to improve.

The missing politics and unsettled science of the trend toward earlier puberty

The age of puberty in many populations has declined steeply over recent centuries and may be declining still. Consequently, today's children tend to experience the hormonal stresses of rapid development at younger ages than did their ancestors, around whose later, if not more gradual, maturation traditional behavioral expectations formed. Little has been made of this "rush to puberty" outside the life sciences. This article reviews its historical documentation, scholarly appreciation, epidemiological correlations, putative physiological and environmental explanations, sociological implications, and largely latent politics.