Participants were followed from year of first birth until 2005. We defined gestational age as very preterm (20 to ≤32 weeks), moderate preterm (33 to ≤37 weeks), term (38 to ≤42 weeks), and postterm (≥43 weeks). We defined low birth weight as an infant born at term weighing less than 5.5 pounds, and we defined macrosomia as an infant born at term weighing 10 pounds or more.