Inter-hospital variations in labor induction and outcomes for nullipara: an Australian population-based linkage study

This study aimed to describe variation in inter-hospital induction of labor (IOL) rates, determine whether variation is explained by individual and hospital factors and examine birth outcomes.

Nullipara at term with a singleton cephalic birth were identified using linked hospital discharge and birth data for 66 hospitals in New South Wales, Australia, 2010-2011. Random effects multilevel logistic regression models were fitted for early term, full term, and late term births, adjusting for individual and hospital factors. Hospital intrapartum cesarean rates, and severe maternal and neonatal morbidity outcomes were determined according to hospital IOL rate.

Of 69 549 nullipara, 24 673 (35%) had an IOL. For early term births, adjusted hospital IOL (aIOL) rates varied (3.3-13.9%), with 11 of 66 (17%) hospitals having aIOL rates significantly different from the average aIOL rate. For births at full term, the hospital aIOL rates varied (10.6-32.6%), with 29 hospitals (44%) having aIOL rates significantly different from the average aIOL rate. For late term births, the hospital aIOL rates varied (45.1-67.5%), with 11 hospitals (17%) having aIOL rates significantly different from the overall average aIOL rate for women with late term births. There was generally no relationship between higher or lower hospital IOL rates and intrapartum cesarean section rates, or maternal or neonatal adverse outcomes.

Inter-hospital IOL rates for nullipara with a singleton cephalic term birth had high unexplained variation, with no clear association with intrapartum cesarean section rates, or maternal or neonatal adverse outcomes.