Increased risks of circulatory diseases in late pregnancy and puerperium

We studied a nationwide Swedish cohort with 654,957 women who had 1,003,489 deliveries from 1987 through September 1995 to assess late pregnancy and p uerperal risks of circulatory diseases. We used standardized incidence rate ratios to calculate relative risks [with 95% confidence intervals (CIs)]. Compared with unexposed (nonpregnant and early pregnant) women, relative ri sks of venous thrombosis and pulmonary embolism Juring the third trimester were 6.1 (95% CI = 5.7-7.8) and 2.7 (95% CI = 1.7-4.2), respectively. Aroun d delivery (from 2 days before to 1 day after delivery), the relative risks of all assessed circulatory diseases were dramatically increased: venous t hrombosis, 115.1 (95% CI = 96.4-137.0); pulmonary embolism, 80.7 (95% CI = 53.9-117.9); subarachnoid hemorrhage, 46.9 (95% CI = 19.3-98.4); intracereb ral hemorrhage, 95.0 (95% CI = 42.1-194.8); cerebral infarction, 33.8 (95% CI = 10.5-84.0); and myocardial infarction, 27.0 (95% CI = 0.6-180.0). Duri ng the rest of the first 6 weeks postpartum, the risks declined but were st ill substantially increased for all diseases, with the exception of subarac hnoid hemorrhage. The results suggest that the increased risk for circulato ry diseases related to pregnancy is mainly confined to a few days around de livery.