The Effect of Very Low Birth Weight and Social Risk on Neurocognitive Abilities at School Age

Abstract

We tested the hypothesis that very low birth weight (VLBW < 1.5 kg) children would have significantly poorer neurocognitive abilities at school age than would normal birth weight full-term age mates, that differences would persist after control for neurologic impairment and social risk, and that VLBW would interact with social risk. Two hundred forty-nine VLBW children and a randomly selected sample of 363 normal birth weight age mates born 1977 through 1979 were tested at 8 years. A neurologic examination and tests of intelligence, language, speech, reading, mathematics, spelling, visual and fine motor abilities, and behavior were performed. Twenty-four (10%) VLBW had a major neurologic abnormality compared with none of the controls. VLBW had significantly poorer scores on all tests, with the exception of speech and the total behavior score. These differences persisted among VLBW children without major neurologic abnormality, with the exception of social competence, reading, and spelling. Even normal IQ, neurologically normal VLBW had significantly poorer scores than did controls in expressive language, memory, visuomotor, and fine motor function, and measures of hyperactivity. When social risk was controlled in multiple regression analyses, VLBW still had an adverse effect on all outcome measures with the exception of speech. Social risk was, however, the major determinant of outcome. We found an interaction between VLBW and social risk only in verbal IQ and in the opposite direction than hypothesized.