Scientists have linked breastfeeding with better receptive language at 3 years of age and verbal and nonverbal intelligence at age 7 years.

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.

Mandy B. Belfort, M.D., M.P.H., 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.

The study said that longer breastfeeding duration was associated with higher Peabody Picture Vocabulary Test score at age 3 years (0.21; 95 percent CI, 0.03-0.38 points per month breastfed) and with higher intelligence on the Kaufman Brief Intelligence Test at age 7 years (0.35; 0.16-0.53 verbal points per month breastfed; and 0.29; 0.05-0.54 nonverbal points per month breastfed). However, the study also noted that breastfeeding duration was not associated with Wide Range Assessment of Memory and Learning scores.

The authors said that 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.

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.

The study has been published in JAMA Pediatrics.