Association for Public Policy Analysis & Management

After increasing for decades, the rate of preterm births (< 37 weeks gestation) in the United States has declined in recent years—from a peak of 12.8% of all births in 2006, to 11.4% in 2013.  Since premature infants are more likely to experience worse immediate and longer term health outcomes, and even death, than full term infants, it is important to understand the underlying causes of this recent downward trend. In this paper, we first document that the decline cannot be attributed to changes in the demographic composition of mothers, and that it is experienced across racial groups.  We then estimate the role of changes in medical practice, cigarette taxes, and public transfers.