Deep vein thrombosis and pulmonary embolism are two clinical entities of a single disease called venous thromboembolism. Venous thromboembolism is an important cause of maternal morbidity and mortality. Diagnosis and treatment of venous thromboembolism in pregnant women are much more difficult than in non-pregnant women. Pregnant patients were excluded from all major clinical trials investigating therapeutic combinations for acute thromboembolism. Although, for many years, the standard anticoagulant during pregnancy and postpartum was unfractionated heparin, current guidelines recommend low molecular weight heparin. The advantages of low molecular weight heparin are lower risk of bleeding, predictable pharmacokinetics, lower risk of fracture because of thrombocytopenia and heparin-induced osteoporosis.