OBJECTIVE:

To validate the risk-adjusted cesarean delivery rate as a measure of obstetric quality through its association with maternal and neonatal outcomes for all pregnancies (model 1) and in primiparous patients with singleton pregnancies (model 2).

METHODS:

We constructed a population-based cohort of 845,651 patients from 401 hospitals representing all deliveries in California and Pennsylvania between 2004 and 2005. We used linked birth certificate and hospital admission records for mother and neonate to estimate the correlation between risk-adjusted cesarean delivery and a composite of adverse maternal outcomes, adverse neonatal outcomes, and four obstetric patient safety indicators from the Agency for Healthcare Research and Quality (AHRQ).

RESULTS:

In both models, risk-adjusted cesarean delivery rates were negatively correlated with both the maternal and neonatal composite outcomes and the AHRQ patient safety indicators for birth trauma, injury with instrumented vaginal delivery, and cesarean delivery. Approximately 60% of the 107 hospitals with lower-than-expected risk-adjusted cesarean delivery rates had higher-than-expected rates of at least one of the six adverse outcomes, compared with 19.6% of the hospitals with higher-than-expected risk-adjusted cesarean delivery rates and 36.1% of the hospitals with expected rates (P<.001).

CONCLUSION:

Lower-than-expected risk-adjusted cesarean delivery rates in all patients or when restricted to a more homogeneous group of primiparous patients with term singleton pregnancies are associated with higher-than-expected adverse maternal or neonatal outcomes. Higher-than-expected risk-adjusted cesarean delivery rates do not result in improved outcomes.