About 13 million babies each year are born prematurely, with preterm birth linked to increases in risk for attention-deficit/hyperactivity disorder (ADHD), problems with social development, and lower grades. A problem with past analyses of prematurity, however, is that they do not capture the variety seen in children born pre-term, including some with outcomes better than the average results for full- term children. Pre-term means birth before 37 weeks of gestation, with full term being 40 weeks.