Unexplored territories in the nonsurgical patient: a look at pregnancy.

Venous thromboembolism (VTE) remains the most common cause of maternal death during pregnancy and the puerperium. The risk is increased in women older than 35 years and those with obesity, previous VTE, operative delivery, and underlying thrombophilia. Anticoagulant therapy is indicated for short-term treatment of VTE and as thromboprophylaxis in high-risk patients. Warfarin is contraindicated during the first trimester because of fetotoxicity; unfractionated heparin (UFH) is associated with practical disadvantages and a risk of heparin-induced thrombocytopoenia (HIT) and osteoporosis with long-term use. Low-molecular-weight heparins (LMWHs) are convenient to use, do not cross the placenta, carry a lower risk of HIT and osteoporosis, and have been shown to be safe and effective during treatment of approximately 500 pregnant women. LMHWs are increasingly replacing UFH as the anticoagulant of choice during pregnancy; further studies are required to determine optimal therapeutic and thromboprophylactic doses. Women with inherited or acquired thrombophilia are at increased risk of severe pregnancy complications, including recurrent miscarriage, pre-eclampsia, fetal growth restriction, abruptio placentae, and stillbirth; uteroplacental microvascular thrombosis caused by thrombophilia appears to be the pathophysiologic link. LMWHs have been shown to improve pregnancy outcome in women with a history of obstetric complications and confirmed thrombophilia. Copyright 2001 by W.B. Saunders Company.