Length Of Reproductive Life Span Research Articles

Association Between Reproductive Life Span and Incident Nonfatal Cardiovascular Disease

Early menarche and early menopause are associated with increased risk of cardiovascular disease (CVD) in midlife, but little is known about the association between reproductive life span and the risk of CVD. To investigate the association between the length of reproductive life span and risk of incident CVD events, while also considering the timing of menarche and menopause. Individual-level data were pooled from 12 studies participating in the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events consortium. Women provided complete information on the timing of menarche and menopause, nonfatal CVD events, and covariates. Cox proportional hazards models were used to estimate hazard ratios and 95% CIs, adjusted for covariates. The association between reproductive life span and CVD was adjusted for age at menarche and age at menopause separately. Analysis began March 2018 and ended December 2019. Reproductive life span was calculated by subtracting age at menarche from age at menopause and categorized as younger than 30, 30 to 32, 33 to 35, 36 to 38 (reference group), 39 to 41, 42 to 44, and 45 years or older. First nonfatal CVD event, including coronary heart disease and stroke events. A total of 307 855 women were included. Overall, the mean (SD) ages at menarche, menopause, and reproductive life span were 13.0 (1.5) years, 50.2 (4.4) years, and 37.2 (4.6) years, respectively. Pooled analyses showed that women with a very short reproductive life span (<30 years) were at 1.71 (95% CI, 1.58-1.84) times higher risk of incident CVD events than women with a reproductive life span of 36 to 38 years after adjustment for covariates. This association remained unchanged when adjusted for age at menarche but was attenuated to 1.26 (95% CI, 1.09-1.46) when adjusted for age at menopause. There was a significant interaction between reproductive life span and age at menarche associated with CVD risk (P < .001). Women who had both short reproductive life span (<33 years) and early menarche (age ≤11 years) had the highest risk of CVD (hazard ratio, 2.06; 95% CI, 1.76-2.41) compared with those with a reproductive life span of 36 to 38 years and menarche at age 13 years. Short reproductive life span was associated with an increased risk of nonfatal CVD events in midlife, and the risk was significantly higher for women with early age at menarche.

Replication of loci influencing ages at menarche and menopause in Hispanic women: the Women's Health Initiative SHARe Study.

Several genome-wide studies have identified loci associated with reproductive traits, such as ages of menarche and menopause, in women of European ancestry. In this study, we investigated the relevance of these loci in minority US Hispanic women. We utilized data from 3468 women who were genotyped as a part of the Women's Health Initiative SNP Health Association Resource. We replicated associations of eight loci (LRP18, LIN28B, CENPW, INHBA, TMEM38B, ZNF483, NFAT5 and OLFM2) with age at menarche, and of two loci (MCM8 and BRSK1/TMEM150B) with age at menopause. The MCM8 locus was also associated with early menopause risk. Three loci (CENPW, MCM8 and BRSK1/TMEM150B) were associated with the length of reproductive lifespan. We provide evidence that genetic variants influencing reproductive traits identified in European populations are also important in minority US Hispanic women.

Sexual Selection and Senescence: Male Size‐Dimorphic Ungulates Evolved Relatively Smaller Molars than Females

As a general rule, males of sexually dimorphic ungulate species have evolved larger body size than females but shorter reproductive life spans as elements of their strategy for intrasexual competition for mating opportunities. Evolutionary theories of senescence predict that the durability of somatic structures should relate to the length of reproductive life span. This prediction has recently been tested for red deer (Cervus elaphus): molariform teeth of males are smaller and less durable than those of females, which corresponds with sex differences in reproductive life span. However, general evidence that male teeth are smaller than expected by allometric rules as a consequence of sexual selection for increasing male body mass requires an interspecific comparison between dimorphic and nondimorphic ungulates. Here we investigate the relationship between cheek-teeth size (occlusal surface area; OSA) and body mass in 123 species of extant ungulates. We found lower slopes for dimorphic species compared with nondimorphic ones and smaller OSA, relative to body mass, in males of dimorphic species compared with females of dimorphic species. Rates of evolution of OSA relative to rates of evolution of body mass were greater in females than in males and also greater in nondimorphic than in dimorphic species. Our results are consistent with the hypothesis that sexual selection in polygynous male ungulates favors body size more than tooth size, with possible consequences in male senescence via early depletion of male teeth compared to females.

Dynamics of Childbearing Statistics in Twentieth Century Developing and Developed Countries

The paper presents the dynamics of childbearing indices in the twentieth century for 23 developing and 35 developed countries. The childbearing process over time is measured by projected ages at first and last birth, and length of reproductive life span, using the model derived by Home, El-Khorazaty, and Suchindran (1990). A time series for each of the three childbearing indices for each country is obtained, using only data on age-specific fertility rates. Two distinct general patterns characterizing childbearing transition are identified, according to variations over time of each index, which simultaneously reflect changes in fertility levels. Future childbearing behavior is forecasted to the year 2000 using ARIMA time series modeling.

Statistical modeling of selected aspects of the childbearing process with application to World Fertility Survey countries.

"A mathematical model for estimation of certain aspects of the childbearing process, which requires only data on age-specific fertility rates, is developed. Synthetic maternal childbearing indices, namely, mean ages at first and last birth, length of reproductive life span, inter-birth spacing, and proportion of childless women, in addition to the well-known mean age at childbearing, for the WFS [World Fertility Surveys conducted in developing] countries are obtained using the proposed model. The indices are free from age truncation effects, and, under certain assumptions, provide information about a cohort's completed fertility before the women stop reproducing. The effects of women's residence and education on fertility are also examined." (SUMMARY IN FRE)