Extremely low birth weight children and their peers: a comparison of preschool performance.

Though not well studied, extremely low birth weight (ELBW; < 1000 g) appears to be a major risk factor for developmental disability, with most affected children experiencing school problems (40% to 64%) rather than severe handicap (25%). This study marks the first published US attempt to document prospectively the developmental/educational progress of a cohort of predominantly white, middle-class ELBW children with randomly selected and matched heavier birth weight (1500 through 2500 g and > 2500 g) peer comparison groups. Sixty ELBW children and 60 peers were administered a test battery at age 4 years, including the McCarthy Scales of Children's Abilities, Peabody Picture Vocabulary Test, and Beery Test of Visual-Motor Integration. The ELBW group mean scores were significantly lower than those of the peer groups on every measure, although generally still within 1 SD of the test mean. Twenty-three percent were clearly disabled; 26% had optimal development, having attained at least average scores on all measures; and 51% attained borderline scores globally or had an average cognitive score, but specifically poor performance in one or more areas. Comparison groups were 2 1/2 times more likely to have optimal development and had mean cognitive scores 15 to 18 points higher than the ELBW group. In summary, weaker performance on all measures exists prior to school entry among nondisabled ELBW children compared with their peers. It is unclear whether these data portend emerging school-based disabilities or describe a continuing recovery process to be completed in middle childhood. Continued follow-up of this cohort at 7 and 10 years of age will address these questions.