Socioeconomic variations in the proportions of stroke attributable to reproductive profiles among postmenopausal women in China.

Background: This prospective study aimed to examine the individual and combined population attributable fractions (PAFs) of stroke and its subtypes associated with reproductive factors among Chinese postmenopausal women, highlighting variations across socioeconomic status (SES) stratas.

Methods: Data were from 138,873 Chinese postmenopausal women enrolled in the China Kadoorie Biobank. Reproductive factors evaluated in this study included early age at menarche, early age at menopause, advanced age at first live birth, high parity, history of stillbirth, history of miscarriage or termination, and non-lactation. PAFs were calculated using hazard ratios, estimated using Cox proportional hazard regression, and prevalence of the seven reproductive factors. PAF for each reproductive risk factor and combined PAFs for all factors were estimated in total population and across SES classes.

Results: Of the 138,873 included participants, 17,042 developed strokes during a median follow-up period of 8.9 years. Across SES classes, the greatest attributable fractions of total stroke cases were observed for high parity among low-SES women (PAF 17.2%, 95% confidence interval [CI] 13.7%, 20.6%), history of miscarriage or termination among medium-SES women (PAF 11.4%, 95% CI 8.2%, 14.5%), and no history of lactation among high-SES women (PAF 3.1%, 95% CI 1.7%, 4.9%). A multiplicatively estimated 20.5% (95% CI 20.4%, 20.5%) and 3.1% (95% CI 1.7%, 4.9%) of stroke cases were attributable to the seven reproductive risk factors in low-SES and high-SES women, respectively.

Conclusions: A large fraction of stroke cases among Chinese postmenopausal women were associated with reproductive factors. Targeted cardiovascular prevention strategies are warranted among women with different SES to mitigate risks associated with different reproductive profiles.