The main risk factors for deep vein thrombosis in pregnancy and after delivery are preeclampsia, operative delivery, adiposity, prolonged bed rest, and haemostatic defects (antithrombin, protein C and protein S deficiencies), activated protein C resistance, lupus anticoagulant/antiphospholipid antibodies. Hyperhomocystinaemia is a general risk factor for deep vein thrombosis. The clinical diagnosis of deep vein thrombosis is difficult and must be confirmed by imaging techniques. Positive D-dimer has high sensitivity, but low specificity to detect acute thrombosis. Standard treatment is unfractionated heparin intravenously for 7-10 days, followed by subcutaneous injections. Anticoagulant treatment is prolonged for 6-12 weeks after delivery, usually with warfarin. During pregnancies associated with high risk of thrombosis, low molecular heparin prophylaxis is given during pregnancy and 6-12 weeks after delivery. Thrombosis in pregnancy must be followed by adequate investigation for an underlying thrombotic predisposition.