The relationship between birthweight, weight gain in infancy, and educational attainment in childhood.

Previous studies have examined the relationship between low weight gain (failure to thrive) in infancy and later cognitive ability, but no study to date appears to have examined the relationship between weight gain in infancy across the 'normal' range and later cognitive ability. We report results for a large prospective birth cohort of the relationship between weight gain in infancy and educational attainment at age 10. Routinely recorded weights from child health clinic records for an annual birth cohort of 3418 children born with gestation >36 weeks were collected, as well as gestation in weeks, birthweight and the postcode, for which the Townsend Deprivation Score was identified. At 10 years of age, those attending schools within the Newcastle Education Authority were given a picture vocabulary and a non-verbal ability test, and tests of educational attainment in maths and reading. These were successfully linked to the infant weight data for 2294 (63%) of the children, and complete growth data were available for 1724 (47%) of the children who had completed at least one educational test. There was a significant positive relationship between weight gain in infancy and picture vocabulary, adjusted for economic deprivation, gestational age and birthweight, but not with any of the other outcomes. There was a statistically significant association between birthweight and all four outcomes, which was positive up to about one SD above average birthweight, and negative above. In this population, the association between early growth and cognitive outcomes is stronger for growth before birth, postnatal weight gain having a relatively minor impact.