Prevention of Venous Thromboembolism and Pregnancy Complications using Low-Molecular-Weight Heparin during Pregnancy: A Systematic Review of Safety and Thromboprophylactic Efficacy.

Introduction Low-molecular-weight heparin (LMWH) is used in pregnancy for venous thromboembolism (VTE) prophylaxis and for prevention of pregnancy complications, because of efficacy greater than or equal to unfractionated heparin, and a lower rate of side effects observed in non-pregnant patients. Due to the lack of data from large randomized controlled trials to guide physician’s practices, there is a need for increased data on safety and efficacy of LMWH for these indications. Our aim was to evaluate the safety and efficacy of using LMWH during pregnancy for preventing VTE and pregnancy complications by performing a systematic review of data from published literature.

Methods Data from published studies on the use of LMWH during pregnancy as VTE prophylaxis or LMWH for prevention of pregnancy complications were identified by searching MEDLINE and EMBASE databases up to the end of 2003. The reference lists from identified articles were also hand searched. Data on the LMWH regime, incidence of VTE, pregnancy complications, clinical outcomes and side effects were extracted and entered into pre-piloted forms.

Results Fifty studies reporting 2,322 pregnancies were included in this analysis. LMWH was received antenatally in 1883 (81%) of cases, and only peri or postpartum in 389 (17%) of cases. Dalteparin and enoxaparin were the most commonly used LMWH, but certoparin, nadroparin, rivaparin, and tinzaparin were also used. There were no maternal deaths. VTE was reported in 26 (1.1%) pregnancies. Severe maternal bleeding occurred in 46 (2%) pregnancies and was generally associated with obstetric causes. Thrombocytopenia occurred in 10 (0.4%) pregnancies and was not associated with thrombosis. Minor allergic skin reactions occurred in 23 (1%) pregnancies, and osteoporosis in two (0.09%) pregnancies.

Conclusion Data from this systematic review of the literature suggest that LMWH is both safe and effective for use as VTE prophylaxis during pregnancy.