Objectives: The association between parity and risk of hemorrhagic stroke (HS) remains to be clarified. This study assessed the association of parity with the overall risk of HS and compared its contribution to intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH).
Methods: We used a database from a nationwide multicenter case-control study, in which 471 female cases with incident HS were matched at 1:2 with 942 community or hospital controls. A total of 459 HS cases and 918 controls with information on parity were included. Parity was categorized as 0-1, 2, 3, and >or=4. Adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated by conditional logistic regression. As potential confounders, age, history of hypertension, history of diabetes, family history of stroke, smoking status, alcohol consumption, educational status, age at menarche, and use of oral contraceptives were included in the models.
Results: Compared with nullipara and unipara, women with parity of 2, 3, and >or=4 had significantly higher risk for total HS, ICH, and SAH, respectively. Each additional parity increased the ORs of HS (adjusted OR for total HS = 1.27 [95% CI 1.14-1.41]; adjusted OR for SAH = 1.34 [95% CI 1.13-1.58]; adjusted OR for ICH = 1.27 [95% CI 1.08-1.48]). Likelihood ratio test for trends showed a significantly increased risk with increasing parity for total HS and for both types of HS (p(trend) < 0.05 in all analyses).
Conclusions: Increased number of childbirths may be related to an increased risk of both intracerebral hemorrhage and subarachnoid hemorrhage.