Pregnancy is an independent risk factor for venous thromboembolism (VTE) due to changes in coagulation and fibrinolysis. These are on the procoagulant side, as are changes in blood flow in the leg veins due to compression of the veins by the pregnant uterus. Some endothelial changes, especially during delivery, are described, too. There are, in addition, some other risk factors related to normal pregnancy, like increased body weight, due to pregnancy-related or concomitant diseases. The incidence of VTE is about 0.1%. Venous thromboembolism could happen during the whole pregnancy, and about half of the events are observed in the six weeks postpartum. Diagnostic procedures to detect VTE start with clinical suspicion, which is probably less reliable than in nonpregnant persons. However, the VTE should be confirmed by objective methods like in nonpregnant persons. For the diagnosis of deep venous thrombosis, the main diagnostic procedure is compression ultrasound, and for suspected pulmonary embolism is computerized pulmonary angiography. D-dimer assessment is less reliable than in the nonpregnant population, but it could be used. In patients with pulmonary embolism, risk assessment for worse outcomes should be performed by using established criteria. Treatment of VTE is specific because direct oral anticoagulant drugs and vitamin K antagonists are contraindicated, and low-molecular-weight heparin is the drug of choice during pregnancy. After delivery, vitamin K antagonists could also be used. Treatment should last during the whole pregnancy and six weeks postpartum or at least three months. In some rare cases of pulmonary embolism, thrombolysis could be used, too.