Cesarean Delivery in Native American Women: Are Low Rates Explained by Practices Common to the Indian Health Service?

Abstract

Studying populations with low cesarean delivery rates can identify strategies for reducing unnecessary cesareans in other patient populations. Native American women have among the lowest cesarean delivery rates of all United States populations, yet few studies have focused on Native Americans. The study purpose was to determine the rate and risk factors for cesarean delivery in a Native American population. We used a case-control design nested within a cohort of Native American live births, > or = 35 weeks of gestation (n = 789), occurring at an Indian Health Service hospital during 1996-1999. Data were abstracted from the labor and delivery logbook, the hospital's primary source of birth certificate data. Univariate and multivariate analyses examined demographic, prenatal, obstetric, intrapartum, and fetal factors associated with cesarean versus vaginal delivery. The total cesarean rate was 9.6 percent (95% CI 7.2-12.0). Nulliparity, a medical diagnosis, malpresentation, induction, labor length > 12.1 hours, arrested labor, fetal distress, meconium, and gestations < 37 weeks were each significantly associated with cesarean delivery in unadjusted analyses. The final multivariate model included a significant interaction between induction and arrested labor (p < 0.001); the effect of arrested labor was far greater among induced (OR 161.9) than noninduced (OR 6.0) labors. Other factors significantly associated with cesarean delivery in the final logistic model were an obstetrician labor attendant (OR 2.4; p = 0.02) and presence of meconium (OR 2.3; p = 0.03). Despite a higher prevalence of medical risk factors for cesarean delivery, the rate at this hospital was well below New Mexico (16.4%, all races) and national (21.2%, all races) cesarean rates for 1998. Medical and practice-related factors were the only observed independent correlates of cesarean delivery. Implementation of institutional and practitioner policies common to the Indian Health Service may reduce cesarean deliveries in other populations.