Reproductive factors and risk of mortality in older women: a 16-year follow-up of Guangzhou Biobank Cohort Study

BACKGROUND: China's dramatic decline in fertility rates due to family planning policies and socioeconomic changes has a significant impact on women's long-term health. We examined the associations of individual reproductive factors and reproductive risk scores (RRSs) with all-cause, cardiovascular disease (CVD), and cancer mortality in Chinese women. METHODS: 19 833 women aged 50+ years from the Guangzhou Biobank Cohort Study were included. Reproductive factors include gravidity, parity, number of abortions, age at first pregnancy, duration of breastfeeding, age at menarche, age at menopause, and contraceptive use. Weighted and unweighted RRS was constructed by 6 reproductive characteristics associated with long-term mortality. Cox models were used to estimate hazard ratios (HRs) and 95% CIs. RESULTS: During an average follow-up of 16.7 years, 4310 deaths occurred. Per one-point increase in weighted RRS was associated with higher risks of all-cause (adjusted HR: 1.05, 95% CI, 1.03-1.07) and CVD mortality (1.07, 1.04-1.10), but not with cancer mortality (1.03, 0.99-1.07). Mortality was higher for 0 or ≥4 pregnancies than 3 pregnancies (1.32, 1.06-1.64 and 1.12, 1.02-1.22), 0 or ≥4 childbirths than 2 childbirths (1.46, 1.20-1.79 and 1.15, 1.05-1.25), ≥4 abortions than 1 abortion (1.16, 1.03-1.30), age at first pregnancy <22 years than 22-29 years (1.21, 1.13-1.30), and breastfeeding duration <3 months than 3-11 months (1.23, 1.09-1.38). Age at menopause was negatively associated with all-cause mortality (0.99, 0.98-1.00 per 1-year increase). CONCLUSION: Reproductive factors, including gravidity, parity, abortion, age at first pregnancy, breastfeeding duration, and menopausal age, were significant determinants of mortality risk in older Chinese women.