BACKGROUND AND PURPOSE - Although it has been suggested that high gravidity and parity increase the risk for coronary heart disease, their associations with stroke are unclear.
METHODS - We evaluated associations of gravidity and parity with incidence of stroke in the Shanghai Women's Health Study (SWHS), a population-based cohort study of 74 942 Chinese women aged 40 to 70 years at enrollment (1996 to 2000). We also examined the association between number of children and stroke prevalence in both SWHS participants and their husbands. Stroke cases were ascertained through in-person interviews and linkage with vital statistics registries.
RESULTS - During a mean follow-up of 7.3 years, 2343 incident cases of stroke were identified. Women with more pregnancies or live births had a significantly increased risk for incident stroke. After adjustment for socioeconomic status and other potential confounders, women with > or =5 pregnancies had a hazard ratio for incident stroke of 1.45 (95% CI, 1.18 to 1.77) compared with those with only one pregnancy. At baseline recruitment, 859 and 1274 prevalent cases of stroke were reported among SWHS participants and their husbands, respectively. Stroke prevalence increased with increasing number of children in both women and men. Adjusted ORs of prevalent stroke for having > or =5 children versus having one child were 1.61 (95% CI, 1.16 to 2.23) in women and 1.45 (1.11 to 1.89) in men.
CONCLUSIONS - High gravidity or parity may be related to increased risk of stroke in women. Chronic stress and adverse lifestyle factors related to childrearing may contribute importantly to the increased risk.