BACKGROUND: The incidence of pregnancy in advanced age among women is increasing because of the availability of assisted reproduction, although the long-term health consequences are not known. OBJECTIVE: The purpose of this study was to determine the effect of pregnancy in advanced age on the occurrence of cardiovascular events in a large cohort of postmenopausal women. STUDY DESIGN: We analyzed the data for 72,221 women aged 50-79 years who were enrolled in the observational arm of the Women's Health Initiative study. We determined the effect of pregnancy in advanced age (last pregnancy at age >= 40 year) on the risk of ischemic stroke, hemorrhagic stroke, myocardial infarction, and cardiovascular death over a mean period (+/- standard deviation) of 12 +/- 1 years using Cox Proportional Hazards analysis after adjusting for potential confounders. RESULTS: A total of 3306 of the 72,221 participants (4.6%) reported pregnancy in advanced age. Compared with pregnancy in normal age, the rates of ischemic stroke (3.8% vs 2.4%), hemorrhagic stroke (1.0% vs 0.5%), and cardiovascular death (3.9% vs 2.3%) were significantly higher among women with pregnancy in advanced age. In multivariate analysis, women with pregnancy in advanced age were 50% more likely to experience a hemorrhagic stroke (hazard ratio, 1.5; 95% confidence interval, 1.0-2.1) after adjustment for age, race/ethnicity, congestive heart failure, systolic blood pressure, atrial fibrillation, alcohol use, and cigarette smoking. There was no significant difference in the risk of ischemic stroke, myocardial infarction, and cardiovascular death among women with pregnancy in advanced age after adjustment for potential confounders. CONCLUSION: Women with pregnancy at an advanced age have a higher risk for hemorrhagic stroke in the postmenopausal period.