Parity, Age at Childbirth, and Later-Life Health-Related Quality of Life in Postmenopausal Women.

Objective: We aimed to examine the long-term effects of parity, age at first childbirth, and age at last childbirth on later-life health-related quality of life (HRQoL) in postmenopausal women. Materials and Methods: The Women's Health Initiative data included 15,416 postmenopausal women with repeated measures in HRQoL. We used propensity score matching to create matched samples, where each exposure group was matched with a reference group based on their propensity scores. We employed mixed-effects models to examine the associations of parity and age at childbirth with HRQoL. We performed multiple mediation analyses to assess the effects of potential mediators on the associations. Results: The overall HRQoL scores of women with parity of 4 and 5+ compared to parity of 2 significantly increased by 1.4 (95% confidence interval [CI]: 0.56-2.24) and 1.3 (95% CI: 0.36-2.24), respectively. Having the last childbirth after 40 was associated with increased overall HRQoL by 2.2 (95% CI: 0.50-4.4). However, the HRQoL for women with age at first childbirth of <20 was reduced by 2.7 (95% CI: 1.66-3.74) compared to age at first childbirth of 25-29. In multiple mediation analyses, we identified the path: age at first childbirth of <20 → premature menopause → reduced HRQoL. Conclusions: The mixed-effects models demonstrated that age at first childbirth of <20 was related to decreased HRQoL over time, while parity of 4 and ≥5 and late age at last childbirth were associated with increased HRQoL. Premature menopause significantly mediated the association between young age at first childbirth and reduced HRQoL.