Socioeconomic variations in reproductive factor-associated burden of ischaemic heart disease among postmenopausal women in China

Reproductive factors may have lifelong implications for cardiovascular health, with variations by socioeconomic status (SES). In this prospective cohort study among 134,405 postmenopausal women in the China Kadoorie Biobank, 14,805 incident ischaemic heart disease (IHD) cases occurred during a median follow-up of 8.94 years. Four of eight reproductive factors were associated with higher IHD risk. The combined population attributable fraction (PAF) was 10.14% (95% confidence interval 7.76%, 12.45%) overall and was highest in the low SES group (14.34%). Early age at first live birth and lifetime breastfeeding for <2 years were leading contributors in the low- and high-SES groups, respectively. Waist circumference, hypertension, and diabetes partially mediated the association between early age at first live birth and IHD, although pathway-specific PAFs were <1%. These findings suggest that reproductive history is associated with substantial and socioeconomically patterned IHD burden, highlighting the importance of SES-sensitive, life-course approaches to women’s cardiovascular prevention.