Inherited thrombophilias are not yet established as a cause of placenta-mediated pregnancy complications, such as fetal growth restriction, preeclampsia, abruption, and pregnancy loss. An inherited thrombophilia is only one of many factors that lead to development of these diseases and is unlikely to be the unique factor that should drive management in subsequent pregnancies. The paucity of evidence for benefit, coupled with a small potential for harm, suggests that low molecular weight heparin should be considered an experimental drug for these indications until data from controlled trials are published. At present, women with a history of placenta-mediated pregnancy complications, with or without a thrombophilia, should be followed closely without routine prophylactic low molecular weight heparin other than for prevention of venous thromboembolism in limited circumstances.