Anticoagulants during pregnancy.

Anticoagulant therapy during pregnancy is problematic because both heparin and oral anticoagulants can potentially produce adverse maternal and fetal effects. Reviewing the relevant literature makes it clear that heparin is safer for the fetus than are oral anticoagulants. For the prophylaxis and treatment of venous thromboembolic disease in pregnant patients, heparin is the preferred anticoagulant because its efficacy and safety are established. However, because the efficacy of heparin in preventing systemic embolism in patients with prosthetic heart valves is not established, either adjusted-dose heparin or a combination of heparin and oral anticoagulants can be used.