Measures obtained from NICU admission include proxies of socioeconomic status (parental public vs. private insurance and home census tract-based estimate of household income) and injury markers. N reflects number of subjects for which the measure was obtained and (for categorical variables) the number of subjects falling into each category. Modified Sarnat Score reflects documented degree of encephalopathy on exam within the first six hours of life (moderate (2) vs. severe (3)). NICHD MRI grade reflects both the degree and gross distribution of brain injury on conventional MRI. Grades include categories for normal MRI (0), cortical/subcortical involvement only (1A (minimal cerebral lesions) and 1B (more extensive cerebral lesions), basal ganglia/thalamic/deep white matter involvement only (2A (basal ganglia, thalamic, internal capsule lesions only), or involvement of both areas (2B (basal ganglia, thalamic, internal capsule, and cerebral lesions) and 3 (cerebral devastation)). Parent-reported household tax bracket and clinical diagnosis of cerebral palsy were obtained from the 2-year research visit.