Birth Weight, Neonatal Intensive Care Units, and Infant Mortality: Evidence from Macrosomic Babies

Abstract

Using a regression discontinuity design, this study estimates the effect of extra medical care on the short-run health of babies born at the high end of the birth weight distribution. Consistent with the notion that neonatal treatment decisions are guided by a rule of thumb when assigning medical care to macrosomic newborns, we find evidence of a large discontinuous jump in the likelihood of being admitted to a neonatal intensive care unit (NICU) as the 5000-gram cutoff is crossed from below. The resulting plausibly exogenous variation in medical care in the vicinity of the 5000-gram cutoff identifies the health effect of additional medical care. Parametric and non-parametric regressions reveal that being born above the 5000-gram cutoff increases the probability of NICU admission by about 30% and decreases the risk of infant mortality by about 130% relative to sample means below the 5000-gram cutoff. The importance of the substantial health gains associated with extra medical care in the macrosomic patient population is likely to grow over time since maternal obesity, a major risk factor for macrosomia, is on the rise.