Increased risk of learning disabilities in low birth weight boys at age 11 years

Background: Few studies have examined learning disabilities among low birth weight (less than or equal to 2500 g) children, and those that have, have focused on very low birth weight children (<1500 gl. We tested the hypothesis that low birth weight increases the risk of reading and math disabilities, examined possible sex differences in the effect of low birth weight, and assessed risk across the entire range of low birth weight. Methods: Low birth weight and normal birth weight children were randomly selected front the 1983-1985 newborn lists of an urban and a suburban hospital in southeast Michigan. Children with neurological impairments were excluded. Children were evaluated at age 6 years and at age II years. Of the 823 children in the initial assessment, 717 (87.1%) participated in the second assessment. The Wechsler Intelligence Scale for Children-Revised and title Woodcock-Johnson Psyche-Educational Battery-Revised were used to identify children with learning disabilities. Learning disabilities were estimated in 574 children with IQs of greater than or equal to 85. Results: Low birth weight was associated with increased risk for reading and math disability in male children (odds ratio = 3.3 and odds ratio = 6.5, respectively) but not in female children. The increased risk of learning disabilities among male children applied to the entire range of low birth weight and was observed in both the urban and suburban communities, Conclusions: The effect of low birth weight on learning disabilities appears to be specific to male children. Although this sex-specific effect is consistent with previous findings of a greater vulnerability of male children to pregnancy and birth complications, it remains to be replicated and clarified. (C) 2000 Society of Biological Psychiatry.