OBJECTIVE: This study was undertaken to determine individual and institutional level variables predictive of variations in nulliparous term singleton vertex cesarean delivery rates. STUDY DESIGN: Retrospective cohort study of 28,863 nulliparous term singleton vertex births at 40 Arizona hospitals. RESULTS: The average nulliparous term singleton vertex cesarean delivery rate was 22.0%, the lowest hospital rate was 10.3%, high, 34.2%. The following individual level variables increased the nulliparous term singleton vertex cesarean delivery rate in a multivariable model: increased mother’s age, African American race, increased birthweight, labor induction, and the presence of medical conditions such as diabetes and hypertension. Of the institutional variables, after adjustment, the highest level of nursery or a higher percentage of government-paid births was associated with lower risks, whereas delivery at a hospital with the lowest level of care or with an obstetric and gynecology residency was associated with an increased risk of cesarean delivery.
