Pulmonary embolism and stroke in relation to pregnancy: How can high-risk women be identified?

OBJECTIVE: Risks of circulatory diseases are increased substantially during late pregnancy and around the time of delivery. This study was undertaken to determine whether preeclampsia, multiple pregnancy, or cesarean delivery account for the majority of pregnancy-related risks of pulmonary embolism and stroke (caused by hemorrhage, infarction, and intracranial venous thrombosis). STUDY DESIGN: We analyzed a population-based cohort of 1,003,489 deliveries in Sweden. Relative risks of pulmonary embolism and stroke were modeled by use of Poisson regression. RESULTS: Preeclampsia was associated with 3- to 12-fold increases in risks of pulmonary embolism and stroke during late pregnancy, at delivery, and in the puerperium, and similar increases in risks were also observed for multiple pregnancies and cesarean delivery. These strong associations could not explain the overall pregnancy-related risks of pulmonary embolism and stroke. CONCLUSION: Preeclampsia, multiple birth, and cesarean delivery are important risk factors for pulmonary embolism and stroke, but they do not account for the majority of the excess risks associated with pregnancy.