Low-Molecular-Weight Heparin in Pregnancy: State of the Art

Abstract

Pregnancy is an acquired hypercoagulable state with a fourto tenfold increased thrombotic risk during gestation and the postpartum period. One out of 1000 women will develop venous thromboembolism (VTE) in association with pregnancy [1] and the risk of a recurrent event during gestation is between 2 and 13% dependent on the nature of the first event [2]. Arterial thrombosis in pregnancy is less common than VTE but with increasing maternal age, prevention and treatment of arterial disease has become an important issue [3]. In addition, the recent association of thrombophilia with pregnancy complications including; miscarriage, pre-eclampsia, placental abruption, intrauterine growth restriction and fetal death, have led to consideration of antithrombotic prophylaxis in a substantial percentage of pregnant women [4]. Platelet antagonists such as aspirin are used in pregnancy in the prevention of arterial thrombosis and in women with antiphospholipid antibody (APLA) syndrome as an adjunct to anticoagulants [5]. Vitamin K antagonists cross the placenta and are associated with fetal malformations in the first trimester and an increased risk of bleeding in the fetus throughout gestation [6]. Therefore, in general, their use is strictly prohibited after 6 weeks of gestation, except in women with mechanical heart valves in whom their use can be considered in the second and third trimester. a i c s t t b