Hypertensive Complications of Pregnancy and Risk of Venous Thromboembolism

Hypertension during pregnancy and preeclampsia are associated with increased arterial thrombotic risk in later life. Whether these complications are associated with risk of venous thromboembolism (VTE) on the short term after pregnancy and on the long term, that is, outside pregnancy, is largely unknown. We conducted a nationwide cohort study in women with at least 1 pregnancy and their first VTE risk by linking the Dutch perinatal registry (Perined) to anticoagulation clinics. We used Cox proportional hazard models to estimate hazard ratios (HRs) and corresponding 95% CI for VTE risk in women with hypertension during pregnancy, women with preeclampsia, compared with women with uncomplicated pregnancies (reference). A total of 1 919 918 women were followed for a median of 13.7 (interquartile range, 7.6-19.2) years for a total of 24 531 118 person-years in which 5759 first VTEs occurred; incidence rate: 2.3 (95% CI, 2.3-2.4) per 10 000 person-years. In the first pregnancy and 3-month postpartum period, VTE risk was higher in women with hypertension, HR, 2.0 (95% CI, 1.7-2.4), and highest among women with preeclampsia, HR, 7.8 (95% CI, 5.4-11.3), versus the reference group. On the long term, women with hypertension during pregnancy and preeclampsia had a higher VTE risk: HR, 1.5 (95% CI, 1.4-1.6) and HR, 2.1 (95% CI, 1.8-2.4), respectively, versus the reference group. When excluding events during pregnancy and postpartum, these HRs were 1.4 (95% CI, 1.3-1.5) and 1.6 (95% CI, 1.4-2.0), respectively. In conclusion, hypertension during pregnancy and preeclampsia are associated with an increased VTE risk during pregnancy and postpartum period and in the 13 years after.