Why is Infant Mortality Higher in the US than in Europe?

The US has a substantial - and poorly understood - infant mortality disadvantage relative to peer countries. We combine comprehensive micro-data on births and infant deaths in the US from 2000 to 2005 with comparable data from Austria and Finland to investigate this disadvantage. Differential reporting of births near the threshold of viability can explain up to 40% of the US infant mortality disadvantage. Worse conditions at birth account for 75% of the remaining gap relative to Finland, but only 30% relative to Austria. Most striking, the US has similar neonatal mortality but a substantial disadvantage in postneonatal mortality. This postneonatal mortality disadvantage is driven almost exclusively by excess inequality in the US: infants born to white, college-educated, married US mothers have similar mortality to advantaged women in Europe. Our results suggest that high mortality in less advantaged groups in the postneonatal period is an important contributor to the US infant mortality disadvantage.