Breastfeeding may not do much for verbal skills

NEW YORK (Reuters Health) - Preschoolers who were breast-fed show stronger verbal abilities than their bottle-fed peers, but the advantage may have more to do with their parents than with breast milk, a new study suggests.

The findings, reported in the journal Pediatrics, suggest that some of the brain benefits that have been attributed to breastfeeding are not solely a result of breast milk nutrients.

Instead, researchers found, mothers who breastfeed tend to have stronger verbal skills themselves, and may be better equipped to promote the same in their children.

"The beneficial effects of breastfeeding on children's cognition may emerge only when breastfeeding is done in conjunction with other positive parenting behaviors," write the study authors, led by Dr. Christina Gibson-Davis of Duke University in Durham, North Carolina.

A number of past studies have linked breastfeeding with higher childhood IQ scores. Certain fatty acids found in breast milk are known to aid nervous system development, and researchers have speculated that this explains the IQ gains.

But it's also possible, Gibson-Davis and her colleagues point out, that general parenting practices are the main factor. For example, mothers who breastfeed tend to be better educated, and they may be more likely to engage their children in "stimulating activities," such as reading.

For their study, the researchers had 1,645 3-year-olds take a standard test of vocabulary; their mothers took the same test, scored according to their age. Investigators visited the families at home to give them the tests, and to rate the home environment.

In general, the study found, children who were breastfed for at least one month scored higher on the vocabulary test than bottle-fed children did -- about 7 points higher, on average.

But the advantage nearly disappeared when the researchers factored in the mothers' test scores, suggesting that maternal verbal ability largely explained the breastfeeding benefit.

In fact, the study found, breastfeeding showed no effect on children's verbal ability when their mother had only a high school education. Only when mothers had some higher education was there a small benefit of breastfeeding on verbal test scores.

"The advantageous effects of breastfeeding do not seem to be solely attributable to the superior nutrient content of breast milk," Gibson-Davis and her colleagues conclude.

The findings do not diminish the importance of breastfeeding, which experts consider the best nutrition for infants. In general, it's recommended that babies be given breast milk exclusively for the first 6 months of life.

However, Gibson-Davis and her colleagues conclude, parenting skills are clearly key in young children's cognitive development, whether they breastfeed or bottle-feed.

SOURCE: Pediatrics, November 2006.