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Age at menopause is associated with a variety of health outcomes. Menstrual histories, both as markers of physiologic function and through their potential association with age at menopause, have also been investigated for their links to health outcomes. This study used data from a cohort of women from the United States who provided prospectively recorded data on their menstrual cycles for many years. Dr. Alan Treloar (University of Minnesota) originally recruited the women in the 1930s; the authors used data reported by these women from 1930 through 1977. They identified nuanced characteristics of menstrual histories that were strongly predictive of the onset of menopause, focusing on measures of central tendency (the mean), variability (standard deviation), and serial irregularity (approximate entropy), the last of which quantifies a continuum that ranges from totally ordered to completely random. They controlled for other characteristics known to affect age at menopause, including use of exogenous hormones, number of births, and extent of breastfeeding. Although cycle length and variability increased with the approach of menopause, the authors found that serial irregularity decreased and was a strong predictor of its onset. This finding constitutes an important piece of information not attainable with conventional statistical summaries of menstrual histories.

The second section of this paper set forth a theoretical model relating adolescent growth and development to family formation patterns and their implications for maternal and child health. Subsequent sections of the paper examine the evidence to support specific relationships hypothesized in the model, focusing on longitudinal data from Matlab, Bangladesh. Despite the emphasis on developing country populations, literature from developed countries was also reviewed. The weight of the evidence suggests that in the developed countries, while there is a positive relationship between reproductive maturation and subsequent reproductive behavior, the negative effects of young maternal age on pregnancy outcome is confounded with socioeconomic factors. Teenage pregnancy, or at least teenage birth, occurs disproportionately among the socially and economically disadvantaged. Moreover, teenage childbearing in the U.S., especially when it occurs outside of marriage, violates social norms, at least in the white population. Poor diet may be a problem in the U.S. but it does not appear to result in notable delays in physical growth and development, delayed or compromised adolescent growth, or late age at menarche. Limited evidence suggests that early menarche may be associated with more rapid onset of mature menstrual cycle activity but these findings have not been replicated elsewhere. In developing countries the situation is quite different. First, early marriage and childbearing are desired and common across most segments of society. Second, malnutrition is widespread, and is sufficiently severe to delay the adolescent growth spurt and raise average age at menarche by two to three years compared with developed country populations. This is certainly the case in Bangladesh. In this setting, several observations regarding the relationship of nutritional status, adolescent development and reproduction have been made. First, undernutrition delays growth and reproductive maturation, and women who mature early (i.e., women with young age at menarche) marry at younger ages than later maturers. In addition, body weight appears to have an independent effect on age at marriage, net of age at menarche, such that relatively heavy women marry at younger ages than their lighter counterparts. Explanations for this finding include correlation between body weight and development of secondary sex characteristics, and perhaps a cultural perception that heavier (i.e., normal body weight) women are more attractive, or healthier, mates. The effect of menarche and nutritional status on marriage gives rise to concern that an improvement in nutritional status, and an increase in the age at menarche, would lead to younger marriage and first birth, and higher lifetime fertility.(ABSTRACT TRUNCATED AT 400 WORDS)