Breastfeeding duration is associated with improved cognitive scores at ages 5-14, even after controlling for maternal socioeconomic position and cognitive ability, said the researchers behind a new study.
Despite previous studies demonstrating an association between breastfeeding and standardized intelligence test scores – with breastfed infants scoring higher on intelligence tests than non-breastfed infants – a causal relationship is still contested.
“There is some debate about whether breastfeeding a baby for a longer period of time improves their cognitive development,” the authors of the new study said. They went on to explain how improved cognitive outcomes in breastfed infants could potentially be explained by other characteristics of the women, such as “socioeconomics and maternal intelligence.”
Important at the population level
For the study, published in the open-access journal PLOS ONE, researchers from the University of Oxford (England) set out to investigate how much these confounders influenced the association between breastfeeding duration and cognitive development.
They analyzed data from the U.K. Millennium Cohort Study on 7,855 infants born in 2000 to 2002 and followed until age 14. They highlighted that although the cohort was not specifically designed to address the association between breastfeeding and cognition, it included information on duration of any breastfeeding, duration of exclusive breastfeeding, verbal cognitive scores at ages 5, 7, 11, and 14, spatial cognitive scores at ages 5, 7, and 11, as well as potential confounders, including socioeconomic characteristics and maternal cognition, based on a vocabulary test.
The researchers discovered that longer breastfeeding durations were associated with higher verbal and spatial cognitive scores at all ages up to 14 and 11, respectively.
After taking the differences in socioeconomic position and maternal cognitive ability into account, those children who were breastfed for longer scored higher in cognitive measures up to age 14, compared with children who were not breastfed. They also found that longer breastfeeding durations were associated with mean cognitive scores 0.08-0.26 standard deviations higher than the mean cognitive score of those who were never breastfed. “This difference may seem small for an individual child but could be important at the population level,” the authors commented.
Modest effect
In the United Kingdom, women who have more educational qualifications and are more economically advantaged tend to breastfeed for longer, said the authors. In addition, they added, this group tends to “score more highly on cognitive tests.”
These differences could explain why babies who breastfeed for longer do better in cognitive assessments. However, they said that in their study, “we found that even after taking these differences into account, children breastfed for longer scored higher in cognitive measures up to age 14, in comparison to children who were not breastfed.”
The authors explained that the association between breastfeeding duration and cognitive scores “persists after adjusting for socioeconomics and maternal intelligence.” However, they pointed out that “the effect was modest.”
A version of this article first appeared on Medscape UK.