Thrombophilia and its treatment in pregnancy.

Pulmonary embolism is the most common cause of maternal death during pregnancy and the puerperium in the industrialized world. The risk of venous thromboembolism (VTE) in pregnancy is 0.05%-1.8%, 6 times greater than in the non-pregnant state. The risk is increased in women over 35 years and those with obesity, previous VTE, operative delivery, or underlying thrombophilia. Women presenting with recurrent miscarriages, preeclampsia, intrauterine growth restriction, abruptio placentae, or stillbirth (all associated with microvascular thrombosis in placental blood vessels) have high incidence (65%) of thrombophilia. About 70% of the women who present with VTE during pregnancy are carriers of hereditary or acquired thrombophilia. Treatment of women with VTE during pregnancy, and especially those with thrombophilia, requires individualized dosing and duration of antithrombotic therapy and the formulation of thromboprophylactic strategies for future pregnancies. Warfarin is contraindicated during the first trimester due to fetotoxicity; unfractionated heparin (UFH) is associated with practical disadvantages and the risk of heparin-induced thrombocytopenia (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 are safe and effective. LMWHs are replacing UFH as the anticoagulant of choice during pregnancy and improve pregnancy outcome in women with a history of obstetric complications and confirmed thrombophilia.