To conduct a population-based assessment of associations of intimate partner violence in the year prior to and during pregnancy with maternal and neonatal morbidity. Data from women giving birth in 26 U.S. states and participating in the 2000 to 2003 Pregnancy Risk Assessment Monitoring System (n = 118,579) were analyzed. Women reporting intimate partner violence in the year prior to pregnancy were at increased risk for high blood pressure or edema (adjusted odds ratio 1.37-1.40), vaginal bleeding (adjusted odds ratio 1.54-1.66), severe nausea, vomiting or dehydration (adjusted odds ratio 1.48-1.63), kidney infection or urinary tract infection (adjusted odds ratio 1.43-1.55), hospital visits related to such morbidity (adjusted odds ratio 1.45-1.48), and delivery preterm (adjusted odds ratio 1.37), of a low-birthweight infant (adjusted odds ratio 1.17), and an infant requiring intensive care unit care (adjusted odds ratio 1.31-1.33) compared with those not reporting intimate partner violence. Women reporting intimate partner violence during but not prior to pregnancy experienced higher rates of a subset of these concerns. Women experiencing intimate partner violence both prior to and during pregnancy are at risk for multiple poor maternal and infant health outcomes, suggesting prenatal risks to children from mothers' abusive partners.