FREQUENCY OF PREGNANCY-RELATED VENOUS THROMBOEMBOLISM IN ANTICOAGULANT FACTOR-DEFICIENT WOMEN - IMPLICATIONS FOR PROPHYLAXIS

Background: It has been reported that women with an inherited deficien cy of antithrombin, protein C, or protein S have an increased risk for developing venous thromboembolic disease during pregnancy and the pos tpartum period. However, because the available data on risk are flawed , it is difficult to define a rational, efficacious, and safe policy a bout prophylaxis for venous thromboembolism in these women. Objective: To determine the frequency of venous thromboembolism during pregnancy and the postpartum period in women with heritable deficiencies of ant icoagulant factors. Design: Retrospective cohort study. Setting: Unive rsity outpatient clinics in the Netherlands and Italy. Participants: 1 29 otherwise asymptomatic female family members of patients with a his tory of venous thromboembolism and an established deficiency of antith rombin, protein C, or protein S. Measurements: Medical history, with s pecific attention to episodes of venous thromboembolism and obstetric history, was taken. The anticoagulant factor status of the study parti cipants was determined. if a patient had an episode of venous thromboe mbolism, subsequent pregnancies in that patient were not analyzed. Res ults: Of the 129 women who participated in the study, 60 had anticoagu lant factor deficiency and 69 did not. In the nondeficient group, 198 pregnancies occurred; 1 of these (0.5%) was complicated by an episode of venous thromboembolism during the postpartum period. In the deficie nt group, 169 pregnancies occurred; 7 of these (4.1%) were complicated by an episode of venous thromboembolism during the third trimester of pregnancy (2 pregnancies [1.2%]) and the postpartum period (5 pregnan cies [3.0%]). The risk for venous thromboembolism was increased eightf old in deficient women compared with nondeficient women (hazard ratio, 8.0 [95% CI, 1.2 to 184]). Conclusions: Anticoagulant factor-deficien t women have an increased risk for venous thromboembolism during pregn ancy and the postpartum period. Although data from an appropriate rand omized clinical trial are lacking, the frequency of venous thromboembo lism seen in deficient women might justify the use of anticoagulative prophylaxis during the third trimester of pregnancy and the postpartum period.