Pakistan's new national family planning experiment

Abstract

A survey of 1, 155 girls aged 10 through 20 was conducted in a rural area of Bangladesh in March, 1976, to assess the impact of nutritional status on the onset of menarche and the association between age at menarche and age at marriage. In recent years there has been an increased age at onset of menarche which appears to have been associated with malnutrition caused by war, postwar inflation, floods, and famine in the period 1971–76. Body weight was highly correlated with the age of onset of menarche. A seasonal trend in onset of menarche was noted with the peak occurring in the winter months corresponding to the largest annual rice harvest. An increased age of marriage was also noted, which may be correlated with the increased age of menarche.     

Adult stature and age at menarche in Zapotec-speaking communities in the Valley of Oaxaca,Mexico, in a secular perspective

Adult stature and the age at menarche among individuals from Zapotec-speaking communities in the Valley of Oaxaca in southern Mexico are considered in a secular perspective. Four sets of observations are utilized: (1) adult stature in males and females from five rural communities; (2) age at menarche in adult women and school girls from a single rural community; (3) earlier studies of adult stature in the Valley of Oaxaca; and (4) estimated stature from long bones excavated in various archaeological sites in the Valley of Oaxaca. There were no significant differences among the five communities for stature; hence, the data were pooled for analysis and comparison. Results of linear regression of stature and stature adjusted for the estimated effects of aging after 30 years of age on year of birth indicate negligible secular changes in either sex. Comparisons with statures from earlier surveys, the earliest dates to 1899, also indicate negligible changes. When adult women are grouped according to age, there are no differences in mean ages at menarche between the older and younger women. Mean age at menarche for the total adult sample is 14.53 ± 0.08 years, which compares favorably with the probit estimate for school girls, 14.70 ± 0.32 years. These results thus suggest virtually no secular change in adult size and maturity of the Zapotec-speaking population in the Valley of Oaxaca over the past 80 years. Differences in stature between contemporary populations and estimated statures from long bones from several archaeological sites in Oaxaca are small, and thus suggests little secular change over the past one to two–thousand years.     

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

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

Correlates and predictors of the age of menarche

In a cross-sectional study of 452 girls between 10 and 16 years of age 36 indices of physical and 50 of mental development were tested for their correlation with age at menarche and chronological age, as well as for their predictive power for estimating menarche by multiple regression analysis. Indices of physical maturity and body weight when adjusted for chronological age showed the highest partial correlation coefficients with age at menarche. Among mental characters which show lower intercorrelations with menarche occurred the highest correlation coefficients for a handmotor factor "Spurennachzeichnen" and a factor "Gruppenabh?ngigkeit" (which indicates a type of social motivation). In general physical and mental factors correlate higher with chronological age than with age at menarche. By multiple regression analysis we determined 14 physical and 25 mental predictors explaining 21% and 17% respectively of the variance of age at menarche. The error of the estimate predicting menarche on body weight without knowledge of onset of menarche is +/- 1 year. Using chronological age in a sample of girls before menarche the error of the estimate only is +/- 6 months. To compare the predictive power of chronological age combined with body weight or with skeletal age the time interval is calculated within which 95% of girls attain menarche. The range of prediction extends from 4.3 to 1 year on chronological age (11-16 years); using mean body weight it can be improved by 1.8 to 6 months, while using mean skeletal age an improvement of 0.2 to 3.9 months is possible compared with body weight. The correlations between age at menarche and physical and mental variables are attributed to a common hormonal influence on rate of development.     

Weight, height, thorax and of menarche in Spanish schoolgirls.

In this paper, the authors study the correlation which exists between somatic development, represented by weight, height and thorax, and the age of onset of menarche. The results indicate that girls showing early menarche have a somatic development greater than the mean. It has also been possible to show that the greatest increase in height occurs before the menarche, while the greatest increase in weight coincides with the appearance of the menarche, or occurs shortly afterwards.     

Menarcheal age of Turkish girls in Bremen

Several studies have shown that there is a Northwest-Southeast gradient in menarcheal age of European girls, with menarche occurring on the average about one year earlier in girls living in the Southern parts of Europe as compared with those from the Northern and Northwestern European countries. Eveleth & Tanner (1976) as well as Danker-Hopfe (1986a) suggested that this gradient is due primarily to genetic differences rather than climatic or nutritional variation. To substantiate this hypothesis menarcheal age of Turkish girls who lived in Bremen for several years has been investigated. The mean age at menarche estimated by probit analysis based on status quo data from n = 494 girls aged from 9.0 to 16.5 years was 12.90 +/- 1.21 years. These results correspond very well to those reported by Neyzi et al. (1975) for girls from Istanbul. On the other hand mean menarcheal age of Turkish girls living in Bremen is distinctly lower than mean age at menarche of urban German girls, living in the same district. In summary the results of the present study support the hypothesis of a predominantly genetic cause for the observed Northwest-Southeast gradient in age at menarche in Europe.     

Association of Obesity with Onset of Puberty and Sex Hormones in Chinese Girls: A 4-Year Longitudinal Study

Objective

To examine the influence of childhood obesity on the early onset of puberty and sex hormones in girls.

Methods

Healthy girls with different percentages of body fat at baseline (40 obese, 40 normal, and 40 lean) were recruited from three elementary schools in Shenyang, China. These girls (mean age 8.5 years) were also matched by height, school grade, Tanner stage, and family economic status at baseline. Anthropometry, puberty characteristics, and sex hormone concentrations were measured at baseline and at each follow-up visit. The generalized estimating equation model and analysis of variance for repeated measures using a generalized linear model were used to determine the differences in puberty characteristics and sex hormones among three groups.

Results

Over 4 years, mean age of breast II onset was earlier among obese girls (8.8 years) than normal girls (9.2 years) and lean girls (9.3 years). The prevalence (%) of early-maturation in the obese, normal, and lean groups was 25.9%, 11.1%, and 7.4%, respectively. Obesity was associated with an increased risk for breast stage II (year 2: RR, 6.3; 95% CI, 1.9–21.1 and year 3: RR, 6.9; 95% CI, 0.8–60.1). None of the girls experienced menarche in the first year; however, by the fourth year 50.0% of obese girls had menarche onset, which was higher than normal weight (27.5%) and lean girls (8.1%). The mean estradiol level increased with age in the obese, normal, and lean groups. The mean estradiol concentration was higher in obese girls than in normal and lean girls throughout the 4-year period (P<0.05).

Conclusions

Childhood obesity contributes to early onset of puberty and elevated levels of estradiol in girls.     

Age at first marriage in Nepal: differentials and determinants

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

Application of a marriage model in rural Bangladesh

The standard marriage model is evaluated with respect to its applicability in Bangladesh, so that reliable and consistent estimates of mean marriage age for females in Bangladesh can be made. The standard marriage model proposes that a person enters the marriage market and waits until marriage occurs. The distribution of age at entry into the marriage market is generally normal. The delays until marriage occurs are modelled as negative exponential distributions. In a population where marriage is universal, the standard schedule of 1st marriage frequencies developed by Coale and McNeil is a close approximation to the convolution of a normal curve and several exponential distributions G(x), the cumulative probability of marriage at age x. Since the standard distribution of age at 1st marriage is closely approximated by the convolution of a normal curve and several negative exponential distributions, the age at entry to the marriage market for females, and whether this is normally distributed, should be examined. 1 cross-sectional study in Bangladesh concludes that onset of menarche determines entry into the marriage market. The proportion of ever married females by single year of age which is available from cross sectional demographic surveys can be fitted to the Coale-McNeil model. Marriages in the rural areas of Bangladesh seem to follow the pattern of entering the marriage market at puberty, then waiting until actual marriage takes place. This model of entries and delays can also be fitted to cross-sectional data from rural Bangladesh. The use of the Coale-McNeil marriage model in rural Bangladesh is appropriate for estimating the mean age of marriage.     

Formula feeding in infancy is associated with adolescent body fat and earlier menarche.

The tempo, level of growth and maturation during adolescence may have important implications to future adult health. The purpose of the study was to examine factors associated with menarche. Three hundred and forty girls, 9 to 14 years old, were selected from all age eligible girls at Kaiser Permanente Oahu (Honolulu). Girls' age, ethnicity, menstrual status and feeding pattern during infancy were obtained by questionnaire. The mean age of girls was 11.5 +/- 1.4 yr and the mean age at menarche among 112 (33%) girls who had reached menarche was 11.6 +/- 1.1 yr. In logistic regression, achievement of menarche was positively explained by age, Asian ethnicity and formula feeding during infancy. In simple linear regression, higher body mass index (BMI) and subcutaneous fat were also positively associated with formula feeding during infancy. The study suggests that girls who were formula fed deposit more body fat than girls who were breast-fed, resulting in early attainment of menarche.     

Secular Trends of Reproductive Indices in Chuvashian Women

In the present cross-sectional study of the Chuvashian rural population, we examined the secular trends of age at menarche, the age at menopause, the reproductive period, and the age of the first marriage of Chuvashian women. The cohort included 745 women aged 18–90 years; age at menarche (N = 653) ranging from 10 to 24 years (mean 15.42 ± 2.11). Data regarding menopausal age was obtained from 316 women born between 1920 and 1950 (mean 48.5 ± 4.6). Statistical analyses included the maximum likelihood estimation and a Whiskers plot. Women born during the second through the fourth decade of the 20th century showed increasing mean values of age at menarche from 15.4 (second decade) up to 16.5 (fourth decade) and after that a decrease of the mean values to 14.0 (ninth decade). The mean values of menopausal age increased from 47.0 (women born from 1920 to 1925) to 49.3 (born from 1945 to 1950). Age at first marriage showed a trend of decreasing age. Our study demonstrated secular trends of age at menarche in Chuvashian women who had matured after World War II and also confirmed secular trends of increased age at menopause and the duration of the reproductive period. Women, whose maturation was during or immediately after World War II, showed a higher age at menarche and a higher dispersion of age at menopause.     

The influence of age at menarche on the fertility of Chinese women

This paper examines the effect of age at menarche on children ever born (CEB). We use data from the 1997 Sample Survey of Population and Reproductive Health conducted by the China Population Information and Research Center and the State Family Planning Commission. Poisson regression models are estimated for 10,919 ever married Chinese Han women. The influence of a woman's age at menarche on her CEB is examined while controlling for the social effects of rural/urban residency, education, her number of fecund years, whether her first birth occurred before or after the initiation of China's one child policy, and her age at first marriage. The results support our hypothesized positive association between age at menarche and CEB. That is, the later a woman's age at menarche, the greater her number of children ever born. Holding the other five independent variables constant, we show that for every additional month in age at menarche, a Chinese Han woman's mean number of children ever born increases by 0.5 percent. Some of the implications of these results are explored.     

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

Abstract

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

Age at menarche in Iceland

The purpose of this study was to elucidate the mean age at menarche in Icelandic girls and compare it with results from other Scandinavian populations as well as in other ethnic groups. The study was performed during the school year 1972-1973 on a cross-sectional sample of 682 girls (aged 8.5 to over 17 years), constituting 9.5% of the girls from the third to eleventh forms in all the primary and secondary schools of Reykjavik. The mean age at menarche in Iceland, elicited by the status quo method, proved to be 13.06 +/- 0.10 years (S.D. 1.17 years). According to the information given by the girls (recall method), the earliest time of menstruation was 9.83 years and the latest 15.17 years, at which age all but one of the girls were menstruating.     

International variability of ages at menarche and menopause: patterns and main determinants.

The purpose of this study was to review published studies on the variability of age at menarche and age at menopause throughout the world, and to identify the main causes for age variation in the timing of these events. We first present a summary table including mean (or median) values of the age at menarche in 67 countries, and of the age at menopause in 26 countries. General linear models showed that mean age at menarche was strongly linked to the mean female life expectancy, suggesting that one or several variables responsible for inequalities in longevity similarly influenced the onset of menarche. A closer examination of the data revealed that among several variables reflecting living conditions, the factors best explaining the variation in age at menarche were adult illiteracy rate and vegetable calorie consumption. Because adult illiteracy rate has some correlation with the age at which children are involved in physical activities that can be detrimental in terms of energy expenditure, our results suggest that age at menarche reflects more a trend in energy balance than merely nutritional status. In addition, we found the main determinant of age at menopause to be the mean fertility. This study thus suggests that, on a large scale, age at menarche is mainly determined by extrinsic factors such as living conditions, while age at menopause seems to be mainly influenced by intrinsic factors such as the reproductive history of individuals. Finally, these findings suggest that human patterns cannot be addressed solely by traditional, small-scale investigations on single populations. Rather, complementary research on a larger scale, such as this study, may be more appropriate in defining some interesting applications to the practical problems of human ecology.     

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

There is increasing evidence that age at menarche has decreased in Europe and the United States during the last century and in Japan over the last several decades. Data from a community-based survey conducted in two rural counties of Anhui Province in China indicate a similar, downward secular trend in age at menarche for Chinese women. The present study shows the mean age at menarche decreased by 2.8 years, from 16.5 to 13.7, over an approximate 40-year time interval. This rapid decrease in age at menarche may partly be due to better nutrition and living standards reflected by the improved socioeconomic standards experienced in China over the past few decades. To test this hypothesis, a number of determinants of age at menarche were assessed; year of birth, literacy status, county of residence, amount of physical labour, general health status, pesticide exposure before age at menarche, and drinking water source were all found to be associated with age at menarche.     

Pubertal growth of the short normal girl

OBJECTIVES: To determine the timing, magnitude and duration of the pubertal spurt for short normal and average height girls, to compare these with Tanner's standard and to investigate predictors of pubertal growth. METHODS: The growth of 46 short normal and 55 control girls, identified at school entry, was monitored throughout puberty. Height and weight were measured at 6-month intervals from which body mass index (BMI) was derived. Annual velocities were calculated and used to estimate the age and magnitude of peak height velocity (PHV). Age of menarche was recorded to the nearest month. Parents provided information on the child's medical and social history. RESULTS: The mean age at PHV, the magnitude of PHV and age at menarche were similar for both groups and close to Tanner's 50th centile values. Pre-pubertal BMI predicted age at menarche for short and control girls, accounting for 17% of the variance. There was a tendency for early maturing girls of average stature to have greater PHV. However, this relationship was not observed in short girls, nor did any other variable, genetic or environmental, predict the timing or magnitude of their pubertal spurt. CONCLUSIONS: Delayed puberty in short normal girls is unlikely and their growth during puberty is comparable to girls of average height. The pubertal variables measured remain close to Tanner's original standards for both groups, suggesting the lack of a secular trend towards earlier puberty in girls. The onset of menstruation is influenced by pre-pubertal BMI. However, the clinician should be aware that short normal girls have normal pubertal growth and that no genetic or environmental variable can predict the timing or magnitude of their growth spurt.     

Body Composition Characteristics During Puberty in Girls and Boys from Eastern Austria

Puberty represents the final stage of sexual differentiation when the individual acquires reproductive capacity. Puberty is not only characterized by maturation of sexual organs and the formation of oocytes and mature spermatozoa, but also by the development of secondary sexual dimorphism. In industrialized countries, the age of puberty has decreased steadily over the last 150 years in association with improved socio-economic conditions. However, the decreased onset of puberty, especially in females, is associated with problematic changes in behaviour such as early onset of sexual activity resulting in high-risk teenage pregnancies. In our study, we analysed the association between body composition (fat tissue and fat-free body mass, estimated by BIA analyses), height, body mass index and fat distribution and signs of puberty such as the timing of menarche in 228 girls and voice breaking and facial hair growth in 191 boys ageing between 10 and 15 years. In both sexes, signs of puberty were associated, highly significantly, with body composition parameters. Nevertheless, marked differences between the two sexes were observed: Female puberty was positively associated with weight status and the absolute and relative amount of body fat, while in males, puberty was positively related with a higher amount of fat-free body mass and a decreased fat mass. Male voice breaking was significantly associated with increased stature, body weight, waist and hip circumference, lean body mass and total body water. In contrast, voice breaking was significantly negatively associated with the fat percentage, the total fat mass and the waist-to-hip ratio. Female menarche was significantly positively associated with increased body weight, weight status, waist and hip circumference and also with increased absolute and relative fat mass, relative hip circumference, lean body mass and total body water. Only the waist-to-hip ratio was significantly negatively associated with the onset of menarche.     

Body composition characteristics during puberty in girls and boys from Eastern Austria

Puberty represents the final stage of sexual differentiation during which time the individual acquires reproductive capacity. Puberty is not only characterized by maturation of sexual organs and the formation of oocytes and mature spermatozoa, but also by the development of secondary sexual dimorphism. In industrialized countries the age of puberty has decreased steadily over the last 150 years in association with improved socio-economic conditions. However, the decreased onset of puberty is, especially in the female sex, associated with problematic changes in behaviour such as early onset of sexual activity and resulting in high risk teenage pregnancies. First of all, the improved nutritional status during childhood is discussed as a major cause for the decrease of puberty onset, whereas the impact of nutritional status especially on female sexual maturity is discussed controversially. In our study we analysed the association between body composition (fat tissue and fat free body mass, estimated by BIA analyses), height, Body Mass Index and fat distribution, and signs of puberty such as the timing of menarche in 228 girls and voice breaking and facial hair growth in 191 boys ageing between 10 and 15 years. In both sexes signs of puberty were highly significantly associated with body composition parameters. Nevertheless, marked differences between the two sexes were observed: Female puberty was positively associated first of all with weight status and the absolute and relative amount of body fat, while in signs of male puberty were related positively with a higher amount of fat free body mass and a decreased fat mass. Male voice breaking was significantly associated with increased stature, body weight, waist and hip circumference, lean body mass and total body water, in contrast voice breaking was significantly negatively associated with the fat percentage, the total fat mass and the waist to hip ratio. Female menarche was significantly positively associated with increased body weight, weight status, waist and hip circumference but also with increased absolute and relative fat mass, relative hip circumference, lean body mass and total body water. Only the waist to hip ratio was significantly negatively associated with the onset of menarche.     

Heritability of age at menarche in girls from the Fels Longitudinal Study

Menarche is the hallmark maturational event of female childhood. Many studies indicated a significant genetic contribution to the timing of the onset of menstruation, but most of these studies were limited by the use of retrospective data and by the use of data from only certain types of relatives (i.e., mothers and daughters, sisters, or twin sisters). The primary goal of this study was to use a modern maximum likelihood quantitative genetic method to estimate the heritability (h(2)) of age at menarche, using familial data collected over the course of the 74-year-old Fels Longitudinal Study. The secondary goal was to review earlier studies of the heritability of age at menarche. The study of the heritability of age at menarche presented here is unique for two reasons. First, because of the Fels Longitudinal Study's serial design, age-at-menarche data were collected prospectively from most participants. Second, because the Fels Longitudinal Study is a family study that has been conducted for decades, age-at-menarche data are available from many types of female relatives spanning multiple households and generations. The best-fitting and most parsimonious quantitative genetic model included provision for a secular decrease in age at menarche, and estimated the h(2) of age at menarche to be 0.49+/- 0.13 (95% confidence interval of h(2),=0.24-0.73). The results of this study are in general agreement with the findings of most previous studies of genetic influences on age at menarche, and suggest that it is reasonable to consider it well-established that approximately half the phenotypic variation among girls from developed nations in the timing of menarche is due to genetic factors.