Breastfeeding linked to childhood intelligence, says study

Previous research has suggested a positive association between how long an infant is breastfed for and their intelligence later in life.

And now a recent study, published in JAMA Pediatrics, shows that children breastfed for longer during their infancy scored higher on language tests at age three and overall intelligence tests at age seven -- even after accounting for their mother's intelligence scores.

"Breastfeeding an infant for the first year of life would be expected to increase his or her IQ by about four points or one-third of a standard deviation," says Dr. Dimitri A. Christakis of the Seattle Children's Hospital in an editorial accompanying the study.

Lead researcher Dr. Mandy Belfort and her colleagues tracked 1,312 Massachusetts women and their babies who were recruited while pregnant in 1999 to 2002. They gave both the children and the mothers intelligence tests.

Also see: Breastfed babies have a greater chance of climbing the social ladder, study says

The researchers found that each extra month of breastfeeding was tied to a 0.21-point improvement on the language exam at age three, and a 0.35-point improvement reading and writing tests at age seven. There was no improvement in visual motor skills and memory skills.

"Given the size of the benefit, I think this should be helpful for women who are trying to make decisions about how long to breastfeed… because there are many factors that go into that decision," Belfort tells Reuters.

“It’s important to point out that breastfeeding is just one factor that influences a child’s intelligence,” she tells Bloomberg.

She also notes that it is unclear why breastfeeding is associated with a higher childhood IQ, but says that it may be related to the nutrients in the milk helping brain development.

Past studies have also found a link with breastfeeding and kids' intelligence, but those didn't always account for the mother's intelligence as a possible contributing factor to the child's IQ.

Also see: Poet performs moving defence of breastfeeding

"The difficulties with any study are, what were the intellectual capacities of the parents, and did this make a difference?" Dr. Ruth Lawrence, a breastfeeding researcher from the University of Rochester Medical Center in New York, tells Reuters.

"This study shows very clearly that when you controlled for all those parameters, breastfeeding still was associated with higher intellectual development."

The researchers findings support Canadian and international recommendations to promote exclusive breastfeeding up to six months and continued breastfeeding up to one year.

Previous research has also made a connection between breastfeeding and a person's social class later in life.