Hormone Rhythms and Breast Cancer Chronoepidemiology: Salivary Progesterone Concentrations in Pre- and Post-Menarchal Girls and in Normal Premenopausal Women

Orcadian and circatrigintan time series of salivary progesterone levels in premenarchal and adolescent girls and healthy mature premenopausal women have been investigated as a possible determinant for breast cancer risk. Circadian variations in progesterone appear to be more random than systematic and estimates of total daily progesterone output are better represented by samples pooled from several 2-hr specimens. Different patterns of circatrigintan progesterone secretion in girls are recognised and relate to those experienced in infertile and fertile women, though their relation to chronological or menarchal age is as yet uncertain. These data suggest that the measurement of salivary progesterone at premenarche, adolescence and maturity is a feasible, though statistically difficult, study for prospective identification of individuals at risk for breast cancer.     

青海藏族青少年骨龄与生长发育关系研究

本文报告了青海省境内,世居在海拔3000-4000米地区的728名7-18岁健康藏族青少年学生的手、腕部骨骼发育情况,对骨化中心出现和骨骺愈合求出了50%出现年龄,并对骨龄与青春期身高突增的关系及与月经初衬潮的关系进行了分析。     

Hormone rhythms and breast cancer chronoepidemiology: salivary progesterone concentrations in pre- and post-menarchal girls and in normal premenopausal women

Orcadian and circatrigintan time series of salivary progesterone levels in premenarchal and adolescent girls and healthy mature premenopausal women have been investigated as a possible determinant for breast cancer risk. Circadian variations in progesterone appear to be more random than systematic and estimates of total daily progesterone output are better represented by samples pooled from several 2-hr specimens. Different patterns of circatrigintan progesterone secretion in girls are recognised and relate to those experienced in infertile and fertile women, though their relation to chronological or menarchal age is as yet uncertain. These data suggest that the measurement of salivary progesterone at premenarche, adolescence and maturity is a feasible, though statistically difficult, study for prospective identification of individuals at risk for breast cancer.     

The biological standard of living in Indonesia during the 20th century: Evidence from the age at menarche

This article analyses long-term changes in the mean age at menarche (MAM) as a biological indicator of changes in the standard of living in Indonesia. It finds that MAM was about 15.5 for birth cohorts in the late-19th century, decreasing to 14.5 by the 1930s, at which level it stagnated until the gradual decrease resumed since the early 1960s to around 12.5 in the mid-2000s. The article considers that long-term improvements in nutrition, educational attainment and health care explain these trends. An international comparison of long-term changes finds that MAM in Indonesia was much lower than in Korea and China until respectively 1970 and 1990, but comparable to Japan until 1950 and to Malaysia until 1930. The article presents reasons why these differences are unlikely to be related to dissimilarities in climate and ethnicity, and concludes that they are indicative of relative standards of living.     

Development of the sexual skin with pubertal maturation in female chimpanzees

We examined the adolescent development of the sexual skin of chimpanzees (Pan troglodytes) by daily observation, evaluation of swelling, and weekly photogrametry. Although the size of swelling differed with the individual, the development of sexual swelling followed four stages: (1) initial stage, the labial region began to show a slight swelling and recovery; (2) labial stage, swelling at the labial region became maximal; (3) anal stage, another swelling center appeared in the anal region and enlarged; and (4) full maturity stage, the labial and anal regions merged into a full swelling. Menarche occurred after the beginning of the anal stage, and the regular cycle was then established. All of the swelling stages and the peak swelling size are regarded as good indicators of reproductive maturation in chimpanzees.     

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.     

Menarcheal age in medio-altitude sample. Comparison with another populations of same province. Cuenca (Spain)

Environmental contributions to variation on menarcheal age were studied in 2018 Spanish girls and women from de Province of Cuenca. (Spain). This province has a big variation in altitude and is one of the most representative as middle-altitude population in Spain. Maturation's delay in high populations is well referenced but there are less studies in European middle-altitude populations. To give news about this topic is the main objective of this paper. Retrospective Method was employed in adult sample and Status-Quo in young population (9 to 15 years old) Another social, nutritional, somatic and educational levels was recording to give a variation contest. Our study shows a significantly variation between the provincial areas. In effect, the population of “Sierra”, the mountain region has the last maturation in the adults (13.45±0.73) as well as in girls (13.26±1.07). Secular change was observed in relation with this parameter., but less intense that in total, of province. We can confirm the utility of the age of menarche as evaluator of human variation in time and ecological situations.     

A tradeoff between reproduction and growth in contemporary Finnish women

Women have been suggested to trade growth in height for reproduction, as an earlier age at menarche and first birth seem to be related to shorter adult stature. Although women likely accrue fitness benefits by maturing and starting reproduction at young age, short adult stature may be selected against by natural and sexual selection later in their life. We studied how age at menarche and first reproduction affected adult height and whether adult height in turn was related to lifetime reproductive success in Finnish women born 1946–1958. Our results show that a delay of 1 year in age at menarche and first reproduction was related to a 0.43- and 0.20-cm increase in adult height, respectively. The sex of the first-born offspring was not related to adult height. Moreover, women gained fitness benefits by starting reproduction early but not by growing tall. These findings among Finnish women are thus compatible with tradeoffs between reproduction and growth, by showing a compromised adult height at the cost of early age at menarche and first birth. However, in these women, natural selection favored those women who traded their stature for young motherhood.     

Hormonal aspects in the causation of human breast cancer: epidemiological hypotheses reviewed, with special reference to nutritional status and first pregnancy

Epidemiology of breast cancer has identified early age at menarche, late first pregnancy, low parity and late menopause as risk factors, but in addition genetic factors, height, weight and living in western countries play a significant role. The international variation in incidence is almost exclusively due to non-genetic factors. Hypotheses in prevention-oriented research are reviewed: 1. obesity-related oestrogen production as a stimulus of the tumour in postmenopausal women; 2. nutritional status and energy expenditure during puberty and adolescence, developed for fertility and fecundity and extended later to breast cancer; 3. reproductive life during early adulthood, age at first pregnancy and its specific effects on breast tissues. The message of preventability of breast cancer is that mammary epithelial differentiation should come early. Our insight concerning events in puberty and early adulthood can be consolidated in one concept on the risk of extended proliferation of breast epithelium during early adulthood in the absence of full differentiation induced by pregnancy. The combined effects of Western-type nutrition, lack of exercise and Western-type women's emancipation sets the stage for breast cancer already at a young age. Since it is unlikely that emancipated women in affluent societies will return to the original life-style of getting pregnant as soon as it is biologically possible, a novel daring way of protection has to be considered. Could a "Breast Differentiation Pill" be developed to offer protection?     

Father absence, parental care, and female reproductive development

This study examines female reproductive development from an evolutionary life history perspective. Retrospective data are for 10,847 U.S. women. Results indicate that timing of parental separation is associated with reproductive development and is not confounded with socioeconomic variables or phenotypic correlations with mothers' reproductive behavior. Divorce/separation between birth and 5 years predicted early menarche, first sexual intercourse, first pregnancy, and shorter duration of first marriage. Separation in adolescence was the strongest predictor of number of sex partners. Multiple changes in childhood caretaking environment were associated with early menarche, first sex, first pregnancy, greater number of sex partners, and shorter duration of marriage. Living with either the father or mother after separation had similar effect on reproductive development. Living with a stepfather showed a weak, but significant, association with reproductive development, however, duration of stepfather exposure was not a significant predictor of development. Difference in amount and quality of direct parental care (vs. indirect parental investment) in two- and single-parent households may be the primary factor linking family environment to reproductive development.