Low birth weight and neurocognitive status at six years of age.

We examined the relationship between low birth weight (LBW) (< or = 2500 g) and specific neurocognitive abilities at 6 years of age in a large-scale nonconcurrent prospective study. In 1990-1992, we randomly selected and evaluated LBW and normal birth weight (NBW) children from the 1983-1985 newborn lists of two major hospitals in southeast Michigan, one serving an urban and the other a suburban population. LBW children (n = 473) scored significantly lower than NBW children (n = 350) on tests measuring language, spatial, fine motor, tactile, and attention abilities, controlling for population site, race, maternal IQ, and education. Gradient relationships were observed across levels of LBW with language, spatial, tactile, and attention tests. Exploratory analysis, using general additive models, revealed that test performance varied within birth weight levels and that performance continued to improve with increased birth weight well above 3000 g. Follow-up assessments as the children mature will shed light on the persistence of these associations and their implications for learning disorders.