Breastfeeding and IQ: Studying the Data

A host of studies have looked at breastfeeding and IQ. "Most of the studies have found an association between breastfeeding and higher IQ," Kramer tells WebMD. But most have been what scientists call observational studies, with children whose mothers chose to breastfeed compared with those children whose mothers chose not to.

Kramer and others say these studies may be affected by differences in the way moms who breastfeed interact with their children and those who don't.

Kramer and his colleagues looked at almost 14,000 children in Belarus who visited 31 hospitals and clinics there. The participants are part of the large-scale study known as the Promotion of Breastfeeding Intervention Trial (PROBIT). The researchers assigned half to an intervention that encouraged them to breastfeed exclusively long term or to another group that got the usual maternity care and child care.

This approach is considered more feasible and ethical than assigning mothers to breastfeed or bottle-feed.

"Those who got the breastfeeding intervention breastfed longer and more exclusively," Kramer says. The number of mothers still breastfeeding exclusively at three months was seven times higher in the intervention group of mothers — 43% compared to 6% of those who didn't get the intervention.