Key PointsQuestionIs socioeconomic deprivation at the neighborhood level, measured by an Area Deprivation Index, an independent risk factor for neonatal intensive care unit (NICU) mortality and morbidity among extremely premature infants?FindingsIn a cohort study of 2765 extremely premature infants (gestational age <29 weeks) admitted to 4 level IV NICUs in different US regions, national Area Deprivation Index percentile was associated with the risk of NICU mortality and morbidities after adjusting for multiple covariates.MeaningThese findings have implications for public health measures, which should target areas of neighborhood deprivation to improve prenatal care with the aim of improving NICU outcomes.