Length of time a mother breast-feeds an infant is linked to the child’s IQ

THE QUESTION Breast-feeding offers children protection against ear infections, gastrointestinal problems, eczema and allergies. Should a higher IQ be added to this list of benefits?

THIS STUDY analyzed data on 1,312 young children, nearly 90 percent of whom had been breast-fed. Overall, their mothers breast-fed for an average of six months, and they did so exclusively, with no formula, for about two months. After taking into account the mothers’ IQ and factors in the children’s home environment that affect cognitive development, intelligence tests given at ages 3 and 7 showed that the children’s scores increased with each additional month they had been breast-fed; this association was especially strong for exclusive breast-feeding. At age 3, the longer children had been breast-fed, the better able they were to comprehend language. By age 7, longer duration of breast-feeding correlated with higher scores on assessments of verbal and nonverbal skills, equaling an IQ about four points higher for children who had been breast-fed for a year than for children who received less breast-feeding.

WHO MAY BE AFFECTED? New mothers and their children. The American Academy of Pediatrics recommends that babies be breast-fed exclusively for the first six months and that breast-feeding continue, supplemented with food, until children are at least a year old. Asthma, obesity and Type 2 diabetes are more common in people who were formula-fed rather than breast-fed.

CAVEATS Data on breast-feeding came from the mothers’ recollections, recorded in interviews and on questionnaires.

FIND THIS STUDY July 29 online issue of JAMA Pediatrics.


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The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment’s effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.