Factor V Leiden (FVL) and prothrombin (PT) G20210A mutations are associated with increased risk of deep venous thrombosis, pulmonary embolism, and obstetric complications. The development of inexpensive and reliable screening methods will assist in defining subpopulations of patients at risk who should undergo testing. We used a method, developed by Abbott Laboratories (Abbott Park, IL), to study 5,000 pregnant women and evaluated the association of obstetric complications with the presence of the FVL and PT G20210A mutations. We found a statistically significant association between FVL and stillbirth. There were also trends toward an association between FVL and placental abruption and between PT G20210A and intrauterine growth retardation. In addition, an association may exist between PT G20210A and preterm delivery for white women. All other parameters studied, including miscarriage and preeclampsia, did not show a statistically significant association with FVL or PT G20210A. These results confirm the association between genetic thrombophilia and selected obstetric complications.