Anticoagulant therapy for venous thromboembolism during pregnancy: a systematic review and a meta-analysis of the literature

Venous thromboembolism (VTE) is one of the most relevant causes of maternal death in industrialized countries. Low molecular weight heparin (LMWH), continued throughout the entire pregnancy and puerperium, is currently the preferred treatment for patients with acute VTE occurring during pregnancy. However, information on the efficacy and safety of anticoagulant drugs in this setting is extremely limited. We carried out a systematic review and a meta-analysis of the literature to provide an estimate of the risk of bleeding complications and VTE recurrence in patients with acute VTE during pregnancy treated with antithrombotic therapy. The weight mean incidence (WMI) of bleeding and thromboembolic events and the corresponding 95% confidence interval (CI) were calculated. Eighteen studies, giving a total of 981 pregnant patients with acute VTE, were included. LMWH was prescribed to 822 patients; the remainder were treated with unfractionated heparin. Anticoagulant therapy was associated with WMIs of major bleeding of 1.41% (95% CI 0.60-2.41%; I) antenatally and 1.90% (95% CI 0.80-3.60%) during the first 24h after delivery. The estimated WMI of recurrent VTE during pregnancy was 1.97% (95% CI 0.88-3.49%; I2 39.5%). Anticoagulant therapy appears to be safe and effective for the treatment of pregnancy-related VTE, but the optimal dosing regimens remain uncertain.