Tables S1 - S3 from Sexual frequency is associated with age of natural menopause: results from the Study of Women's Health Across the Nation

It is often observed that married women have a later age of natural menopause (ANM) than unmarried women; however, the reason for this association is unknown. We test an original hypothesis that sexual frequency acts as a bio-behavioural mediator between marital status and ANM. We hypothesize that there is a trade-off between continued ovulation and menopause based on the woman's chances of becoming pregnant. If a woman is sexually inactive, then pregnancy is impossible, and continued investment in ovulation would not be adaptive. In addition, we test an existing hypothesis that the observed relationship is due to the exposure to male pheromones. Data from 2936 women were drawn from 11 waves of the Study of Women's Health Across the Nation, which is a longitudinal study conducted in the United States. Using time-varying Cox regression, we found no evidence for the pheromone hypothesis. However, we did observe that women who reported to have sex weekly during the study period were 28% less likely to experience menopause than women who had sex less than monthly. This is an indication that ANM may be somewhat facultative in response to the likelihood of pregnancy.

已有研究普遍观察到，已婚女性的自然绝经年龄（age of natural menopause, ANM）晚于未婚女性，但二者关联背后的机制尚不明确。本研究检验了一项原创假说：性行为频率在婚姻状况与自然绝经年龄之间发挥生物-行为中介作用。我们基于女性受孕概率提出相关假说：持续排卵与绝经之间存在权衡关系——若女性无性行为，则无法受孕，此时持续维持排卵的生理投入不具备适应性意义。此外，本研究还检验了一项已有假说：前述婚姻状况与自然绝经年龄的关联源于女性接触男性信息素。本研究数据源自美国开展的纵向研究《全美女性健康跨生命周期研究》（Study of Women's Health Across the Nation）的11轮随访，共纳入2936名女性的相关数据。通过时变Cox回归分析，本研究未发现支持信息素假说的证据。但研究观察到，报告称研究期间每周有性行为的女性，其绝经风险较每月性生活不足1次的女性低28%。该结果提示，自然绝经年龄或许具备一定的兼性可塑性，可随女性受孕可能性的变化而调整。