Early rapid growth: no association with later cognitive functions in children born not small for gestational age.

Background: There is an association between rapid growth in early life and overweight in childhood. This adverse association needs to be balanced against potential beneficial effects on cognitive functioning observed in children who are born small for gestational age (SGA).

Objective: We examined potential beneficial effects of rapid growth on cognitive functions in non-SGA children.

Design: We performed a systematic literature search of 3 databases. In addition, we analyzed data from the Avon Longitudinal Study on Parents and Children (ALSPAC). The association of rapid weight or length gain (defined as an increase of gt 0.67 in the SD score of weight or length between birth and the age of 25 mo) on intelligence quotient (IQ) measurements at 49 mo and 8 y (n = 836 and n = 701, respectively) was assessed in linear models adjusted for potential confounders.

Results: We identified 14 studies that assessed associations between any kind of early weight gain and cognitive outcome and that included non-SGA children. No study explicitly examined the effect of rapid weight gain. In the ALSPAC data, there was no positive association between rapid weight gain and IQ scores at either 49 mo [effect estimate (95% CI): minus 1.4 ( minus 3.6, 0.7)] or 8 y [ minus 0.8 ( minus 3.4, 1.9)] in non-SGA children. Subgroup analyses with stratification by sex of the children yielded similar results, as did analyses with rapid length gain. Supplementary analyses showed no linear association between weight gain and IQ.

Conclusion: We showed no evidence that proposed adverse effects of rapid growth regarding later overweight will be counterbalanced by beneficial effects on cognitive functions in non-SGA children.