School-age outcomes in children with birth weights under 750 g

Abstract

Background: Since the mid-1980s, increasing numbers of children with birth weights under 750 g have survived to school age.

Methods: We matched a regional cohort of 68 surviving children born from 1982 through 1986 with birth weights under 750 g (mean, 670 g; gestational age, 25.7 weeks) with 65 children weighting 750 to 1499 g at birth and 61 children born at term. Growth, neurosensory status, and functioning at school age in the three groups were compared. Associations of biologic and social risk factors with major developmental outcomes were examined by means of logistic-regression analyses.

Results: Children with birth weights under 750 g were inferior to both comparison groups in cognitive ability, psychomotor skills, and academic achievement. They had poorer social skills and adaptive behavior and more behavioral and attention problems. The mean (+/- SD) Mental Processing Composite score for the cohort was 87 +/- 15, as compared with 93 +/- 14 for children with birth weights of 750 to 1499 g and 100 +/- 13 for children born at term (P < 0.001). The rates of mental retardation (IQ < 70) in the three groups were 21, 8, and 2 percent, respectively; the rates of cerebral palsy were 9, 6, and 0 percent; and the rates of severe visual disability were 25, 5, and 2 percent. Major cerebral ultrasonographic abnormalities were associated with mental retardation (odds ratio, 5.4; 95 percent confidence interval, 1.8 to 15.8) and cerebral palsy (odds ratio, 15.2; 95 percent confidence interval, 3.0 to 77.4). Oxygen dependence at 36 weeks was associated with mental retardation (odds ratio, 4.5; 95 percent confidence interval, 1.2 to 10.7) and severe visual disability (odds ratio, 4.3; 95 percent confidence interval, 1.3 to 14.2). Social disadvantage, though associated with several neuropsychological outcomes, was not associated with major developmental impairment.

Conclusions: Children with birth weights under 750 g who survive represent a subgroup of very-low-birth-weight children who are at high risk for neurobehavioral dysfunction and poor school performance.