The trial was extended through December 1997 to allow four years of follow-up. The follow-up allowed the assessment of a primary outcome variable in the neurologic domain and a primary outcome variable in the developmental domain. The primary outcome variable of the neurologic examination resulted in an ordered classification of three categories of normal, minor, and major dysfunction, such as apraxia or cerebral palsy. Development was assessed using standardized measures of cognition, behavior, language, attention, and motor skills. The primary outome variable for the developmental evaluation was the intelligence quotient on the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-R). Secondary outcome variables included measurements of behavior and performance in specific domains of speech and language, visual motor integration, attention, motor function, and temperament.