Pregnancy-Related Venous Thromboembolism Risk in Asymptomatic Women With Antithrombin Deficiency: A Systematic Review.

To evaluate the risk of pregnancy-associated venous thromboembolism in women with asymptomatic antithrombin deficiency.The search was performed on MEDLINE (Ovid and PubMed databases) for the period 1966 to June 2012 and ClinicalTrials.gov as of December 15, 2015.A systematic review including randomized controlled trials, cohort studies, and case-control studies was conducted. Selection criteria included objectively diagnosed venous thromboembolism or venous thromboembolism treated with 3 months of anticoagulation before the availability of objective testing. The study population consisted of pregnant women with asymptomatic antithrombin deficiency.Seven publications were included in the review. No randomized controlled trials were identified. The best available data consist of three retrospective cohort studies and four case-control studies. Pooled results from case-control studies yielded an estimated odds ratio for venous thromboembolism of 6.09 (95% confidence interval 1.58-23.43). No pooled estimates could be obtained for cohort studies. Data on use of thromboprophylaxis were scarce.Despite the small number of patients included, and the variation in study designs, pooled results from case-control studies show a significant association between asymptomatic antithrombin deficiency and pregnancy-associated venous thromboembolism. Thromboprophylaxis during pregnancy and postpartum should be considered in these women.