The purpose of this study was to explore the relationship between religious affiliation and obstetric outcome. We reviewed 1,919 records of patients whose infants were born at a university medical center. Data obtained from maternal and newborn records included demographic information, prenatal history, labor and delivery records, and religious affiliation. Maternal complications and neonatal intensive care unit (NICU) admissions were lowest for mainline Christians (11%, 11%), intermediate for evangelical Christians (17%, 12%), and highest for patients with no religious preferences (21%, 18%). After controlling for possible confounders, the association of religious affiliation and lower NICU admission rates remained. Mainline Christians had a lower frequency of maternal complications. Patients with a religious affiliation had better obstetric outcome than those without. Most of the association seems to be due to a lower risk social profile, but a small positive influence of religion persisted.