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

OBJECTIVE: To evaluate the risk of pregnancy-associated venous thromboembolism in women with asymptomatic antithrombin deficiency.

DATA SOURCES: 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.

METHODS OF STUDY SELECTION: 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.

TABULATION, INTEGRATION, AND RESULTS: 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.

CONCLUSION: 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.