Objective: To assess the association between obstetricians' years of experience after training and the maternal complications of their patients during their first 40 years of post-residency practice.
Design: Retrospective cohort analysis.
Setting: Obstetrical discharges from acute care hospitals in Florida and New York between academic years 1992 and 2009.
Population: 6,704,311 deliveries performed by 5175 obstetricians.
Main outcome measure: Three composite measures of maternal complication rates per physician year from vaginal and cesarean births separately and combined, adjusted for secular trends.
Results: Obstetricians' maternal complication rates declined during the first three decades after completion of residency. The improvement was largest in the first decade and diminished thereafter. For all deliveries, the change was -0.21 (95% confidence interval -0.23 to -0.19) percentage points per year in the first decade, -0.11 (-0.13 to -0.09) percentage points per year in the second decade, and -0.05 (-0.08 to -0.01) percentage points in the third decade (P<0.001 for second to first decade comparison; P=0.001 for third to second decade comparison). The patterns were comparable for cesarean deliveries and vaginal deliveries and across several sensitivity checks.
Conclusions: Among obstetricians practicing in Florida and New York, those with more years of experience had fewer maternal complications. This association persisted over the first three decades of practice but diminished in magnitude.