Inherited thrombophilias are a heterogeneous group of coagulation disorders that predispose individuals to thromboembolic events. This group of conditions is the major risk factor for thromboembolism during pregnancy and the puerperium. In addition, thrombophilias have been associated with several adverse obstetric events, including pregnancy loss, preeclampsia, placental abruption, and intrauterine growth restriction. An increased risk for these obstetric complications has prompted many authorities to recommend screening and treating pregnant women for thrombophilias. Optimal obstetric management, however, is controversial as thrombophilias are common and many affected individuals are asymptomatic. Indeed, pregnancy outcome in most women with thrombophilias is normal. The most commonly identified inherited thrombophilias are the factor V Leiden and prothrombin G20210A gene mutations. More rare thrombophilias include protein C and S deficiencies, antithrombin III deficiency. Although relatively common, the association between hyperhomocysteinemia and associated mutations (such as the C677 T methylenetetrahydro-folate reductase) and obstetric complications is controversial.