Pregnancy is a condition of excessive clotting due to a decrease of some coagulation factors and a reduction of anticoagulant proteins, such as protein S. It is known that the causes of congenital or acquired thrombophilia may be associated with an increased risk of venous thromboembolism during pregnancy and/or obstetric complications, such early or late fetal loss, intrauterine fetal deaths, pre-eclampsia, fetal growth restriction. During pregnancy the use of a prophylaxis with antithrombotic drugs is considered at present a promising opportunity to significantly reduce the prevalence of thromboembolic complications, improving maternal and fetal outcomes. This article is a review to most recent evidence of pregnant anticoagulant prophylaxis in women with previous thromboembolic events.