Enoxaparin use in pregnancy: state of the art.

Low-molecular-weight heparin is the anticoagulant of choice in pregnancy. Enoxaparin has been increasingly used over the past 20 years in pregnant women at risk of thrombosis and pregnancy complications. The main indications are prophylaxis of venous thromboembolism and prevention of pregnancy loss in thrombophilic women. Other indications include treatment of venous thromboembolism, prophylaxis of arterial thrombosis in pregnant women with mechanical heart valves and prevention of late gestational complication such as pre-eclampsia and intrauterine growth restriction. Enoxaparin does not cross the placenta and is safe for the fetus. Maternal side effects are uncommon and include mild localized allergic reactions in 2% and increased bleeding in 2%, which is dose dependent. Heparin-induced thrombocytopenia is very rare and bone resorption is not clinically relevant. The mechanisms of action of enoxaparin in pregnancy are multiple and include anti-factor Xa (anti-Xa) activity in maternal circulation, tissue factor pathway inhibitor release from endothelial cells and trophoblasts at the placental level as well as anti-inflammatory effects.