Secular change in menarche in women in Madrid

Reproductive pattern of Cuban women living in the municipality of Plaza de la Revolución, Havana, Cuba

This paper assesses the reproductive and abortion patterns of women living in Plaza de la Revolución, a municipality of Havana, Cuba, by studying the factors influencing birth and abortion rates. Socio-demographic data and female reproductive histories were collected in a survey of 1200 post-menopausal women living in the municipality. Average ages at menarche and at menopause were 12.71 and 48.39 years, respectively, thus yielding a potential long reproductive period of 35.68 years, indicating high fertility. Although the mean pregnancy rate was 3.81 pregnancies per woman, the live birth rate at time of delivery was only 1.89 due to the high rate of abortions: 40% of all pregnancies were voluntarily interrupted. Among the biological and socio-cultural variables that were found to influence the rate of live births were those related marriage pattern, especially age at first union. Demographic variables such as pregnancy order, maternal age and marital status were the main determinants of the abortion pattern, with abortion being used as a method of birth control in order to obtain the desired family size, and most women (75.2%) using contraceptives.

Decline in age at menarche among Spanish women born from 1925 to 1962

BACKGROUND

While the timing of reproductive events varies across populations, a downward trend in age at menarche has nevertheless been reported in most of the developed world over the past century. Given the impact of change in age at menarche on health conditions, this study sought to examine secular trends in age at menarche among women living in Navarre (Northern Spain) who participated in a population-based breast cancer screening programme.

METHODS

The study was based on 110545 women born from 1925 to 1962. Trends were tested using a linear regression model, in which year of birth was entered continuously as the predictor and age at menarche (years) as the response variable, using size of town and region of birth as covariates.

RESULTS

Among women born in Navarre between 1925 and 1962, age at menarche declined steadily from an average of 13.72 years in the 1925-1929 birth-cohorts to 12.83 years in the 1958-1962 birth-cohorts. Controlling for size of town or city of birth, age at menarche declined by an average of 0.132 years every 5 years over the period 1925-1962. This decline was greater in women born in rural versus urban settings. Trends were also different among regions of birth.

CONCLUSION

We report a population-based study showing a downward trend in age of onset of menarche among Spanish women born in the period 1925-1962, something that is more pronounced among women born in rural settings and varies geographically.

Timing of pubertal maturation in girls: an integrated life history approach

Life history theory provides a metatheoretical framework for the study of pubertal timing from an evolutionary-developmental perspective. The current article reviews 5 middle-level theories--energetics theory, stress-suppression theory, psychosocial acceleration theory, paternal investment theory, and child development theory--each of which applies the basic assumptions of life history theory to the question of environmental influences on timing of puberty in girls. These theories converge in their conceptualization of pubertal timing as responsive to ecological conditions but diverge in their conceptualization of (a) the nature, extent, and direction of environmental influences and (b) the effects of pubertal timing on other reproductive variables. Competing hypotheses derived from the 5 perspectives are evaluated. An extension of W. T. Boyce and B. J. Ellis's (in press) theory of stress reactivity is proposed to account for both inhibiting and accelerating effects of psychosocial stress on timing of pubertal development. This review highlights the multiplicity of (often unrecognized) perspectives guiding research, raises challenges to virtually all of these, and presents an alternative framework in an effort to move research forward in this arena of multidisciplinary inquiry.

The influence of socioeconomic and nutritional status on menarche in Nigerian school girls

A study of 352 randomly selected secondary school girls in an urban population in Southern Western Nigeria revealed a mean menarcheal age of 13.94 +/- 1.31 years and that 76.8% of girls attained menarche between ages 13 and 15 years. Age-matched pre- and post-menarcheal girls did not differ significantly in biophysical measurements, however, nutritional status was strongly and positively associated with attainment of menarche. School girls from the upper socio-economic class reached menarche 11 months earlier than the lower socio-economic counterparts. A significant finding of this study is that the declaration rate in age at menarche was slowest in girls from high socio-economic households. This deceleration was not influenced by body mass suggesting that socio-economic factors play a unique role in the secular trend widely reported in menarcheal age.