Hospital variation in extremely preterm birth

Given that regionalization of extremely preterm births (EPTBs) is associated with improved infant outcomes, we assessed between-hospital variation in EPTB stratified by hospital level of neonatal care, and determined the proportion of variance explained by differences in maternal and hospital factors.

We assessed 7,046,253 births in California from 1997 to 2011, using hospital discharge, birth, and death certificate data. We estimated the association between maternal and hospital factors and EPTB using multivariable regression, calculated hospital-specific EPTB frequencies, and estimated between-hospital variances and median odds ratios, stratified by hospital level of care.

Hospital frequencies of EPTB ranged from 0% to 2.5%. Between-hospital EPTB frequencies varied substantially, despite stratifying by hospital level of care and accounting for confounding factors.

Our results demonstrate differences in EPTBs among hospitals with level 1 and 2 neonatal care, an area to target for future research and quality improvement.