Female reproductive factors and risk of all-cause and cause-specific mortality among women: The Japan Public Health Center-based Prospective Study (JPHC study)

Abstract

Purpose: We investigated the association between reproductive history and mortality from all and major causes among Japanese women.

Methods: A large-scale population-based cohort study in Japan included 40,149 eligible women aged 40-69 years in 1990-1994. A total of 4788 deaths were reported during follow-up (average 20.9 years). A Cox proportional hazards regression model was used to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CI) for all-cause and major causes of mortality, adjusting for potential confounders.

Results: Inverse associations with all-cause mortality were found in parous women (0.74 [0.67-0.82]), women with two or three births compared with a single birth (2 births: 0.88 [0.78-0.99]; 3 births: 0.83 [0.74-0.94]), parous women who breastfed (0.81 [0.75-0.87]), women who were older at menopause (0.88 [0.80-0.97]; p-trend: <0.01), and women who had a longer fertility span (0.85 [0.76-0.95]; p-trend: <0.01). A positive association was seen between all-cause mortality and later age at first birth (≥30 years) than early childbearing (≤22 years).

Conclusions: Our study suggests that parous, two or three births, breastfeeding, late age at menopause, and longer reproductive span are associated with lower risk of all-cause of mortality.

Keywords: Breastfeeding; Cohort Studies; Japan; Menarche; Menopause; Mortality; Parity; Prospective Studies; Reproductive factors.