Study: Breast-fed babies smarter at ages 3 years and 7 years

CHICAGO — Breast-feeding longer is associated with better receptive language at 3 years of age and verbal and nonverbal intelligence at age 7 years, according to a study published by JAMA Pediatrics Monday. 

Mandy Belfort, of Boston Children's Hospital, and colleagues examined the relationships of breastfeeding duration and exclusivity with child cognition at ages 3 and 7 years. They also studied the extent to which maternal fish intake during lactation affected associations of infant feeding and later cognition. Researchers used assessment tests to measure cognition.

Evidence supports the relationship between breastfeeding and health benefits in infancy, but the extent to which breastfeeding leads to better cognitive development is less certain, according to the study background.

"Longer breastfeeding duration was associated with higher Peabody Picture Vocabulary Test score at age 3 years … and with higher intelligence on the Kaufman Brief Intelligence Test at age 7 years," Belfort reported. However, the study also noted that breastfeeding duration was not associated with Wide Range Assessment of Memory and Learning scores. 

As for fish intake (less than 2 servings per week vs. greater than or equal to 2 servings), the relationship between breastfeeding duration and the Wide Range Assessment of Visual Motor Abilities at 3 years of age appeared to be stronger in children of women with higher vs. lower fish intake, although this finding was not statistically significant, the results indicated.

"In summary, our results support a causal relationship of breastfeeding in infancy with receptive language at age 3 and with verbal and nonverbal IQ at school age," Belfort concluded. "These findings support national and international recommendations to promote exclusive breastfeeding through age 6 months and continuation of breastfeeding through at least age 1 year."