Owing to the physiologic changes associated with pregnancy there is a considerably elevated risk of thrombosis during pregnancy and immediately after childbirth. Familial or acquired thrombophilia, i.e. tendency for thrombosis, increases the risk of pregnancy-related thrombosis. Recommendations for the prevention of pregnancy-related venous thromboses are not uniform - the risk of thrombosis must thus be evaluated on an individual basis. Critical clinical consideration should be undertaken when exploring familial thrombophilia in connection with pregnancy complications. Investigation of antiphospholipid antibodies is recommended in connection with certain pregnancy complications.