Care coordination services that link pregnant women to health-promoting resources, avoid duplication of effort, and improve communication between families and providers have been endorsed as a strategy for reducing disparities in adverse pregnancy outcomes, however empirical evidence regarding the effects of these services is contradictory and incomplete. This study investigates the effects of maternity care coordination (MCC) on pregnancy outcomes in North Carolina. Birth certificate and Medicaid claims data were analyzed for 7,124 women delivering live infants in North Carolina from October 2008 through September 2010, of whom 2,255 received MCC services. Propensity-weighted analyses were conducted to reduce the influence of selection bias in evaluating program participation. Sensitivity analyses compared these results to conventional ordinary least squares analyses. The unadjusted preterm birth rate was lower among women who received MCC services (7.0% compared to 8.3% among controls). Propensity-weighted analyses demonstrated that women receiving services had a 1.8% point reduction in preterm birth risk; p less than 0.05). MCC services were also associated with lower pregnancy weight gain (p = 0.10). No effects of MCC were seen for birthweight. These findings suggest that coordination of care in pregnancy can significantly reduce the risk of preterm delivery among Medicaid-enrolled women. Further research evaluating specific components of care coordination services and their effects on preterm birth risk among racial/ethnic and geographic subgroups of Medicaid enrolled mothers could inform efforts to reduce disparities in pregnancy outcome.