Variations in birth weight within the normal range are related to visual orienting in infancy for boys but not for girls [An article from: Infant Behavior and Development]

This digital document is a journal article from Infant Behavior and Development, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Pooling across 27 experiments on visual orienting during early infancy generated a large sample of full-term infants with birth weights greater than 2500g (N=944). A weight-for-date measure was obtained separately for girls and for boys by residualizing birth weight on gestational age at birth. The proportion of trials with orienting toward a moving target increased directly with this weight-for-date measure for boys but not for girls in a linear regression with adjustments for gestational age at testing, birth order and visual stimulus parameters across experiments. The same relations held when raw birth weight was used as a predictor. For the 475 boys, the z-score of the orienting measure increased by 0.221 for each kilogram increase in birth weight corrected for gestational age (0.196 z-units per kilogram adjusted for covariates, 95% CI=0.04-0.35 z-units per kg, P=0.014). The interaction of gender and birth weight in this association makes explanations based on confounding family social variables less tenable as explanations. This association primarily for boys is similar to recently reported associations between birth weight and IQ during childhood. Possible factors underlying this association such as prenatal nutrition are discussed.