The Safety of Low-Molecular-Weight Heparin during and after Pregnancy

Importance In industrialized countries, venous thromboembolism remains a leading cause of mortality in pregnant women. Low-molecular-weight heparin (LMWH) is the most commonly recommended anticoagulant in pregnancy, having been proven effective and safe in multiple prospective clinical trials. Objective The aim of this article is to outline existing recommendations for proper use of LMWH in pregnancy and data on risks of LMWH. Evidence Acquisition We reviewed guidelines from a number of professional societies. We also examined the current literature behind the various risks associated with LMWH use. Results and Conclusions Our review outlines the current data that guide the use of LMWH in pregnancy. With prophylactic dosing, LMWH comes with a 0.5% risk of antepartum bleeding and a 1% risk of postpartum hemorrhage that is not different from clinical trial controls. With treatment dosing, there is a 1.5% risk of antepartum bleeding and a 2% risk of postpartum hemorrhage. Overall, current evidence behind these risks is limited, and this review suggests areas of further study moving forward. Target Audience Obstetricians and gynecologists, family physicians. Learning Objectives After completing this activity, the learner should be better able to define the specific risk factors and preexisting conditions that would warrant LMWH use in pregnancy and postpartum; describe the different available doses of LMWH, when to use each dose, and when monitoring is appropriate; and discuss the risks of anticoagulation with LMWH during various stages of pregnancy and birth.