Abstract
Regionalization ofperinatal care is widely assumed to be an effective means of improving pregnancy outcomes. However, due to limitations of the research designs employed in previous studies aimed at empirically confirming this conventional wisdom, strong evidence concerning the impact of regionalization on pregnancy outcomes is still lacking. In this article an interrupted time-series design is used to assess the impact of regionalization of perinatal care on infant and early neonatal mortality in Central New York. The analysis indicates that regionalization has had a statistically significant, grad ual permanent impact on both infant and early neonatal mortality.