Mandy B Belfort of Boston Children's Hospital and colleagues examined the relationships of breastfeeding duration and exclusivity with child cognition at ages three and seven years.
Researchers found seven-year-olds breastfed for the first year of life were likely to score four points more in a test of verbal IQ. Verbal intelligence scores in seven-year-olds increased by 0.35 points for every extra month of breastfeeding and 0.29 points per month on the nonverbal one.
"In summary, our results support a causal relationship of breastfeeding in infancy with receptive language at the age of three and with verbal and nonverbal IQ at school age," researchers said.
The study was published by JAMA Pediatrics, a JAMA Network publication.