Current ecology, not ancestral dispersal patterns, influences menopause symptom severity

Post-marital residence patterns and the timing of reproduction: evidence from a matrilineal society

Humans exhibit a broad range of post-marital residence patterns and there is growing recognition that post-marital residence predicts women's reproductive success; however, the nature of the relationship is probably dependent on whether co-resident kin are cooperators or competitors. Here, we explore this relationship in a Tibetan population, where couples practice a mixture of post-marital residence patterns, co-residing in the same village with the wife's parents, the husband's parents or endogamously with both sets of parents. Using detailed demographic data from 17 villages we find that women who live with only their own parents have an earlier age at first birth (AFB) and age at last birth (ALB) than women who live with only their parents-in-law. Women who co-reside with both sets of parents have the earliest AFB and ALB. However, those with co-resident older siblings postponed reproduction, suggestive of competition-related delay. Shifts to earlier reproductive timing were also observed in relation to the imposition of family planning policies, in line with Fisherian expectations. Our study provides evidence of the costs and benefits to women's direct fitness of co-residing with different kin, against a backdrop of adaptive responses to cultural constraints on completed fertility.

The relationship between social support, stressful events, and menopause symptoms

Many women going through the menopausal transition experience vasomotor symptoms (VMS), and research has shown that there is a large amount of variation in their frequency and severity. Many lifestyle factors have been found to co-vary with VMS, including the level of social support received by the woman, and how stressed she is. Stress is well documented to worsen menopause symptoms, and there is some evidence that support eases them; however, there is little research into whether support is an effective buffer against the negative effects of stress on VMS. Using nine years of data from the Study of Women’s Health Across the Nation (n = 2718), we use multilevel Poisson regression with random effects to test: 1) if more social support is associated with decreased VMS frequency, 2) if increased life stress worsens VMS, and 3) if support acts as a buffer against stress. After adjusting for age, marital status, smoking, self-perceived overall health, ethnicity, and menopausal status, we find that stress increases the frequency of VMS. Contrary to our hypothesis, we did not find strong evidence that emotional support led to lower VMS frequency, or that support buffers against the effects of stress. Experience of a stressful event, but not amount of social support, was included in the best fitting model; with the degree to which the woman was upset by the life stressor having the largest effect on menopause symptoms. Here, women who said they were currently upset by a stressful event experienced 21% more VMS than women who had experienced no life stressor. This research highlights that social factors may impact the menopausal transition.

Individual and additive-effect relationships of sleep problems and severe menopausal symptoms among women in menopausal transition

OBJECTIVE

Sleep problems and menopausal symptoms are both common complaints among midlife women. However, the associations of the quality and quantity of sleep problems with the severity of menopausal symptoms have not been well studied. Thus, this study aims to examine the relationships between individual sleep problems and the additive number of sleep problems with severe menopausal symptoms among women during the menopausal transition.

METHODS

Using the convenience sampling, a total of 848 middle-aged women in China were investigated from December 2017 to August 2018. All participants completed a questionnaire on sleep problems, Menopause Rating Scale, and the general information questionnaire. Based on the cutoff of the Menopause Rating Scale, participants were divided into the nonsevere menopausal symptom group and severe menopausal symptoms group. Propensity score matching was used to balance covariates between the two groups. Stepwise binary logistic regression and restricted cubic spline were applied to analyze the associations of individual and additive sleep problems with severe menopausal symptoms.

RESULTS

After propensity score matching, no significant difference was observed between the nonsevere menopausal symptoms group and severe menopausal symptoms group (Ps > 0.05). Logistic regression analysis showed that five sleep problems ("feeling too hot," "having pain," "restless legs syndrome," "taking medicine to help sleep," and "having trouble staying awake") were closely associated with severe menopausal symptoms. The restricted cubic spline curve showed an upward trend in odds ratios between the number of these five sleep problems and severe menopausal symptoms, and women were more than twice as likely to suffer severe menopausal symptoms when they experienced more than three of these individual sleep problems.

CONCLUSION

Both the individual and additive number of sleep problems exerted significant effects on severe menopausal symptoms. It might be useful for healthcare providers to set guidelines to support a healthy menopausal transition for midlife women.

The evolutionary ecology of age at natural menopause: implications for public health

Evolutionary perspectives on menopause have focused on explaining why early reproductive cessation in females has emerged and why it is rare throughout the animal kingdom, but less attention has been given to exploring patterns of diversity in age at natural menopause. In this paper, we aim to generate new hypotheses for understanding human patterns of diversity in this trait, defined as age at final menstrual period. To do so, we develop a multilevel, interdisciplinary framework, combining proximate, physiological understandings of ovarian ageing with ultimate, evolutionary perspectives on ageing. We begin by reviewing known patterns of diversity in age at natural menopause in humans, and highlight issues in how menopause is currently defined and measured. Second, we consider together ultimate explanations of menopause timing and proximate understandings of ovarian ageing. We find that ovarian ageing is highly constrained by ageing of the follicle - the somatic structure containing the oocyte - suggesting that menopause timing might be best understood as a by-product of ageing rather than a facultative adaptation. Third, we investigate whether the determinants of somatic senescence also underpin menopause timing. We show that diversity in age at menopause can be, at least partly, explained by the genetic, ecological and life-history determinants of somatic ageing. The public health implications of rethinking menopause as the by-product rather than the catalyst of biological ageing are discussed.