The longer moms exclusively breast-fed their babies, the better those children did at age 3 on a vocabulary test, and at age 7 on an intelligence test, a study says.
“Our results support a causal relationship of breast-feeding duration with receptive language and verbal and nonverbal intelligence later in life,” the researchers reported Monday in the Journal of the American Medical Assn. Pediatrics.
Breast-feeding a baby for a year would be expected to mean an increase in IQ of about four points, the researchers found. Put another way, at age 7, the benefit of breast-feeding was 0.35 points per month on the verbal scale and 0.29 points on the nonverbal scale.
In a provocative accompanying editorial, Dr. Dimitri Christakis of the Seattle Children’s Research Institute noted that such benefits of breast-feeding as lessened problems with gastroenteritis and ear infections have not gotten women in the developed world -- who don’t see breast-feeding as a matter of life or death for their babies -- to follow the recommendations of the World Health Assn. and the American Academy of Pediatrics.
There’s long been a discussion about the effects of breast-feeding on a child’s intelligence, and the researchers said that frequently studies fail to consider confounding conditions such as the mother’s intelligence and the amount of stimulation and support in the home. This study took those into account.
It also looked at the effects on the child of the amount of fish the mother ate during lactation, because fish is a rich source of a fatty acid known as DHA, or docosahexaenoic acid, that may benefit the developing brain.
The study assessed 1,312 mothers and children from a study group in Massachusetts called Project Viva. The scientists were from several institutions, including Boston Children’s Hospital, Harvard Medical School and the Harvard School of Public Health.
When the children were 3, they were given picture vocabulary tests and other tests of intelligence. And at 7, they were given tests to measure verbal and nonverbal intelligence. With the mothers, researchers assessed intelligence, health and diet, and they observed their homes.
The study found no important association between breast-feeding and visual motor skills or visual memory, they said.
The cognitive effects of being breast-fed are lifelong, Christakis wrote.
“It is clear that a vicious cycle can be created wherein lack of breast-feeding begets lower IQ, which begets lower socioeconomic status and thereby decreases the probability of breast-feeding the next generation and so on,” he wrote.
He noted that many women breast-feed their newborns, but when the babies are 6 months of age, only 35% of women are still doing so. He called for insurance coverage of visits by public health nurses and breast pumps, as well as places and opportunities at workplaces for women to pump milk when away from their children. Breast-feeding in public should be destigmatized, he said -- perhaps through a clever social media campaign.
“Let’s allow our children’s cognitive function be the force that tilts the scale, and let’s get on with it.” he concluded.