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.

Birthweight, time-varying adiposity growth and early menarche in girls: A Mendelian randomisation and mediation analysis

OBJECTIVE

To explore the causal effect of time-varying z-BMI growth on early menarche using Mendelian randomisation (MR); to identify critical adiposity predictors of early menarche; to compare the effects of birthweight and time-varying z-BMI growth as mediators of the path from genes to early menarche using mediation analysis.

METHODS

We used data from the Taiwan Children Health Study with 21 obesity-related single-nucleotide polymorphisms (SNPs) to yield genetic (instrumental variable)IVs for adiposity. Children with available data on genotyping, birthweight, adiposity, and menarcheal age were included.

RESULTS

In MR analyses, results based on the time-varying z-BMI growth show more statistical power and capture more information of adiposity growth (p=0.01) than those based on single point z-BMI (p=0.02). Among adiposity measures, critical predictors of early menarche are fat free mass (RR=1.33, 95% CI 1.07-1.65) and waist/height ratio (RR=1.27, 95% CI 1.03-1.56). Other potential predictors of early menarche are sum of skinfold (RR=1.24, 95% CI 1.03-1.48) and total body fat (RR=1.20, 95% CI 1.05-1.38). In both one-mediation and multi-mediation analyses, time-varying z-BMI growth in the prepubertal years plays a crucial mediator in the pathway from the genes to early menarche.

CONCLUSIONS

This study discovered that greater prepubertal adiposity growth is a crucial mediator in the path from genes to early menarche. For girls with genes positively associated with obesity; and/or of lower birthweight, a strategy to prevent childhood adiposity should be implemented in order to avoid early menarche development.

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.

Trends of age at menarche and association with body mass index in Chinese school-aged girls, 1985-2010

OBJECTIVES

To estimate the shifts in age at menarche from 1985 to 2010, compare the differences of average age at menarche between urban and rural groups, and determine the association of menarche with body mass index (BMI).

STUDY DESIGN

The data were obtained from 4 cross-sectional Chinese National Surveys on Students' Constitution and Health (1985, 1995, 2005, and 2010). In this representative sample of Chinese school-aged girls, the average age at menarche was determined using probit analysis and compared between urban and rural areas. Logistic regression was used to assess the association of BMI with the likelihood of having reached menarche.

RESULTS

The age at menarche in Chinese girls dropped from 13.41 years to 12.47 years from 1985 to 2010. There was a significant difference in age at menarche between urban and rural girls over time, with urban girls having their menarche earlier than rural girls. Logistic regression showed that a higher BMI was strongly associated with an increased likelihood of having reached menarche, even after controlling for age, urban or rural residence, province, social economic status, and school.

CONCLUSION

The analysis suggests a drop of about 4.5 months per decade in the average age at menarche over the past 25 years, and a significant inverse association between BMI and having reached menarche. Considering that both early menarche and higher BMI are significant risk factors for chronic diseases, and may act together in later years to the detriment of a woman's health, greater attention should be paid to the health of girls with earlier menarche and higher BMI.

Using heart-rate feedback to increase physical activity in children

OBJECTIVE

The objective of this study was to test whether heart-rate feedback prompts increased physical activity (PA) in primary school students.

METHODS

A controlled trial with 210 9-11 year olds from subsidized Hong Kong Government primary schools was completed in December 2006. Schools were randomly assigned to one of three groups: Control (CG); Educational program (EG); No-educational program (NEG).

INTERVENTION

In a short-term school-based intervention, heart-rate feedback was given either in combination with an educational program (EG) or in isolation (NEG). Long-term retention was assessed in comparison to the control group after 6 months follow-up.

MAIN OUTCOME MEASURES

Physical activity and changes in attraction to PA.

RESULTS

In the short-term, heart-rate monitor feedback increased total daily PA by an average of 24% (p<0.001) and vigorous PA by 0.6% (p<0.05). No change was found for moderate PA. Increases occurred regardless of involvement in the educational program, and in the absence of any change in attitudes towards PA. No long-term retention was apparent.

CONCLUSIONS

The findings from the study suggest that feedback from heart-rate monitors encourages low intensity PA, but when removed increases do not persist.

Peak oxygen uptake in relation to age, sex, and maturation in Hong Kong Chinese children

This cross-sectional study was designed to provide baseline information on peak oxygen uptake for Southern Chinese children in relation to age and sexual maturation. Sixty-three boys and 84 girls, classified for stage of sexual maturation using Tanner's stages, successfully completed a peak oxygen uptake test. ANOVA was used to examine differences in absolute and mass-related peak VO(2). The least-squares log-linear relationship between mass and peak VO(2) was examined using analysis of covariance. We found no difference between boys' and girls' peak VO(2) prior to puberty. Absolute peak VO(2) values for under-10-year-old Chinese girls and boys were 17% and 19%, respectively, lower than Caucasian predicted values. Log-linear adjusted means for prepubertal boys and girls were 34% and 33% lower than Caucasian boys and girls, respectively. By adolescence, values were comparable to Caucasian values. South Chinese children show a distinct pattern of development relative to Caucasian children, particularly in the younger age groups.

Pubertal height gain: male-female and interpopulation comparisons

Data are not available as to the exact age of the start of the pubertal growth spurt (or age at its conclusion) in various populations. As an initial approach, contribution of the pubertal gain to overall height was examined, using age 9 as the start of puberty in girls and age 11 in boys. Data were analyzed from 11 reports (single assays on five populations, two studies on a group analyzed 30 years apart, and four studies of a population spread over 31 years. Using the percent contribution to overall height, pubertal growth showed a close agreement between the populations as well as between male and female values (overall p < 0.003). Results for both sexes clustered around a narrow range. Pubertal growth for the 50th percentile, expressed as a percent contribution to overall height, may approach a biologic invariant. The value of percent contribution of pubertal growth to final height, did not show a secular trend.

Somatic comparisons of South Korean children and youths born and reared in a rural area with the descendants of rural to urban migrants

During April-May 2000 somatic data were collected on 236 males and 191 females ages 6, 9, 13, and 15 years residing in rural areas around the communities of Ankye, Euisung, and Kunwi in Kyungsang Puk Do province, South Korea, and 237 males and 219 female of the same ages born and reared at Taegu in families of "rural to urban migrants." Comparisons were made between urban and rural groups for measures of body size and form, skinfold thickness, the body mass index (BMI), and estimated arm muscle area (ARM). Age at menarche was obtained from school records for the 13- and 15-year-olds. The data were analyzed in separate 2 (urban-rural) x 4 (age) analyses of variance with an alpha level of P < 0.01. Age differences were significant for all dimensions. There was a significant main effect for urban-rural differences in arm girth, upper limb index, and ARM. Rural males were larger in these variables. Among females, only arm girth was significantly different. Age at menarche was significantly earlier in the urban sample (12.6 years) than in the rural sample (13.0 years). Compared with both recent and earlier data for South Korea, present-day 6-, 9-, 13-, and 15-year-old males and females are taller and heavier at every age, indicating secular gains.

Age at spermarche and comparison of growth and performance of pre- and post-spermarcheal Chinese boys

The prevalence of first ejaculation emission (spermarche) in Chinese Han boys in 1995 was considered. The subjects were 86,744 Han boys 9 through 18 years randomly selected from 28 provinces. Median spermarcheal ages (MSAs) were 14.4 and 14.6 years for urban and rural boys, respectively, and 14.3, 14.6, and 14.7 years for the boys of 1st, 2nd, and 3rd socioeconomic classes, respectively. Two environmental factors, ecological and socioeconomic, had strong influence upon MSAs. Eight indicators of somatic growth and motor ability were compared between pre- and post-spermarcheal boys of the same age. Post-spermarcheal boys were advanced in body size, shape, and physiological function during early and middle puberty, but most of the difference disappeared by 16 years. Pre-spermarcheal boys in a given age group were more linear and had more potential for increasing leg length into late adolescence. Within an age group, post-spermarcheal boys had advanced performances in several tasks requiring endurance, strength, and power around the age of maximum growth, 13-15 years. At older ages, the groups did not differ.

[Age at menarche among schoolgirls from a rural community in Southeast Brazil]

The purpose of this study was to determine the 3rd percentile (P3), 50th percentile (P50 = median age at menarche = MAM), and amplitude between the extremes (P97 and P3) of age at menarche among schoolgirls in the county of Barrinha, São Paulo, Brazil. Values were correlated with socioeconomic conditions such as social class, number of siblings, and father's employment status. This was a cross-sectional study based on the use of status quo adjusted by logit for calculation of percentiles. A questionnaire was applied to 1,602 schoolgirls aged 8 to 17 years (incomplete). MAM was 12 years (y) and 6 months (m), with a P97 of 10 y and 2 m and a P3 of 14 y and 10 m. Girls from lower-income families and those with unemployed fathers showed later MAM. No difference in MAM was observed with respect to number of siblings. Amplitude between P97 ad P3 was great in the overall sample. We conclude that Barrinha presented a MAM similar to and even lower than regional values for Brazil and for some developed countries. The study of the interval between extreme percentiles proved to be a better indicator of biological diversity and socioeconomic inequality than MAM alone.

Somatic comparisons at four ages of South Korean females and females of other Asian groups

Somatic data were collected during April 1997 on 156 females ages 6, 9, 13, and 15 years, residing in urban Pusan, South Korea, and on 158 age peers residing in rural regions surrounding the city. Comparisons were made between urban and rural groups for measures of body size and form, skinfold thicknesses, the body mass index (BMI), and estimated arm muscle area (ARM). Age at menarche was retrospectively reported by the 13- and 15-year-olds. The data were analyzed in 2 (urban-rural) x 3 (age) analyses of variance with an alpha level of P < 0.05. Age differences were evident for all dimensions. A significant main effect for urban-rural differences was found for stature, lower limb height, upper limb height, shoulder width, hip width, triceps skinfold, ARM, skelic index, and the trunk width index. Regardless of age, urban children were larger than rural children. Similar means were obtained for the BMI in urban and rural girls. Age at menarche was consistent with recent results; however, the rural sample (12.4 years) was significantly earlier than the urban sample (13.1 years). Compared with data collected four decades ago, present-day 6-, 9-, 13-, and 15-year-old females are taller and heavier at every age, indicating secular gains. Pusan females are similar in stature to age peers in Taiwan, Japan, and Hong Kong, and taller than the Chinese. Am. J. Hum. Biol. 11:735-744, 1999. Copyright 1999 Wiley-Liss, Inc.

Anthropometric measurement error and the assessment of nutritional status

Anthropometry involves the external measurement of morphological traits of human beings. It has a widespread and important place in nutritional assessment, and while the literature on anthropometric measurement and its interpretation is enormous, the extent to which measurement error can influence both measurement and interpretation of nutritional status is little considered. In this article, different types of anthropometric measurement error are reviewed, ways of estimating measurement error are critically evaluated, guidelines for acceptable error presented, and ways in which measures of error can be used to improve the interpretation of anthropometric nutritional status discussed. Possible errors are of two sorts; those that are associated with: (1) repeated measures giving the same value (unreliability, imprecision, undependability); and (2) measurements departing from true values (inaccuracy, bias). Imprecision is due largely to observer error, and is the most commonly used measure of anthropometric measurement error. This can be estimated by carrying out repeated anthropometric measures on the same subjects and calculating one or more of the following: technical error of measurement (TEM); percentage TEM, coefficient of reliability (R), and intraclass correlation coefficient. The first three of these measures are mathematically interrelated. Targets for training in anthropometry are at present far from perfect, and further work is needed in developing appropriate protocols for nutritional anthropometry training. Acceptable levels of measurement error are difficult to ascertain because TEM is age dependent, and the value is also related to the anthropometric characteristics of the group of population under investigation. R > 0.95 should be sought where possible, and reference values of maximum acceptable TEM at set levels of R using published data from the combined National Health and Nutrition Examination Surveys I and II (Frisancho, 1990) are given. There is a clear hierarchy in the precision of different nutritional anthropometric measures, with weight and height being most precise. Waist and hip circumference show strong between-observer differences, and should, where possible, be carried out by one observer. Skinfolds can be associated with such large measurement error that interpretation is problematic. Ways are described in which measurement error can be used to assess the probability that differences in anthropometric measures across time within individuals are due to factors other than imprecision. Anthropometry is an important tool for nutritional assessment, and the techniques reported here should allow increased precision of measurement, and improved interpretation of anthropometric data.