RESUMO
Early term birth is defined as birth at 37 or 38 weeks gestation. While infants born early term are not considered premature, the medical literature suggests that they have an increased risk of serious adverse health outcomes compared to infants born at term (39 or 40 weeks). Despite these known harms, we document a rise in early term births in the United States from 1989 to the mid-2000s, followed by a decline in recent years. We posit that the recent decline in early term births has been driven by changes in medical practice advocated by the American College of Obstetricians and Gynecologists, programs such as the March of Dimes' "Worth the Wait" campaign, and by Medicaid policy. We first show that this pattern cannot be attributed to changes in the demographic composition of mothers, and provide some evidence that efforts to reduce early term elective deliveries (EEDs) through Medicaid policy were effective. We next exploit county-level variation in the timing of these changes in medical practice to examine the effect of early term inductions (our proxy for EEDs) on infant and maternal health. We find that early term inductions lower birth weights and increase the risks of precipitous labor, birth injury, and required ventilation. Our results suggest that reductions in early term inductions can explain about one-third of the overall increase in birth weights between 2010 and 2013 for births at 37 weeks gestation and above.