Health Science Reviews

by Jae Eun Park

Breastmilk – the optimal natural source of nutrition for babies – is known to be beneficial for the physical health of both the baby and the mother. But did you know breastfeeding can also positively affect your child’s cognitive development?

What do existing studies say?

Studies have shown that breastfeeding can boost children’s intelligence quotient (IQ). However, academic achievement, well-being and quality of life depend on more than just IQ – one’s language skills, non-verbal intelligence and executive functions (higher-order functions such as memory and planning) also play a role. However, research done on these three aspects are limited and some are even conflicting. Therefore, a study was done to determine if breastfeeding is beneficial for cognitive development by examining if the duration of breastfeeding during children’s first two years of life had an impact on the abovementioned three cognitive skills in children aged between 5 and 15 years old.

How was the study done?

Data were obtained from a longitudinal cohort study done in Australia. Information about the total duration of breastfeeding (in months) was obtained from interviews with mothers. Children in the study took a vocabulary test at 5, 7 and 9 years old to test their language skills. A reasoning test was done at 7, 9 and 11 years old to test for non-verbal intelligence. Six components of executive functioning, namely: overt attention, working memory, spatial working memory, learning efficiency, and error monitoring, were tested at 15 years old through 3 cognitive tests.

Two linear mixed-effects regression models were used in order to investigate the association between duration of breastfeeding and language skills as well as non-verbal intelligence. Three linear models were used for each of the three tests used to study the association between breastfeeding duration and executive functions.

The covariates considered in this study, amongst others, included the child’s sex, birth weight, gestational age, their exact age at testing, whether the mother drank alcohol and/or smoked during the pregnancy, and the level of the mother’s and father’s education. These covariates were used as control variables in the statistical model so that the effect of breastfeeding alone on cognitive development could be studied.

What did this study show?

A longer duration of breastfeeding was associated with greater language skill scores in children between 5 and 9 years old. This may be due to mothers using infant-directed speech, which is different from the type of speech used between adults, when breastfeeding her baby. This intimate interaction with her child may help the baby regulate their emotions and develop their language skills.

Additionally, an increased duration of breastfeeding was associated with higher non-verbal intelligence scores in children between 9 and 12 years old. This effect may be more pronounced in older children compared to younger children, as previous studies which did not show this association were done on younger age-groups. This association may be due to the effect of nutrients found in breastmilk. Previous studies showed that breastfed children tended to have a greater overall brain volume and grey matter volume than children who were bottle-fed. The positive effect of breastfeeding on brain development may explain both language skill and non-verbal intelligence development.

However, there was no demonstrated effect of breastfeeding duration on the performance in the three tests measuring executive function. Previous studies showing a positive effect of breastfeeding on cognitive functioning were done on younger children, so it may be that the effect is only pronounced in younger ages. Also, executive functioning includes may different cognitive skills; perhaps the six skills tested in this study were not necessarily affected by breastfeeding duration compared to other executive functions.

What the study didn’t show

This study showed a clear dose-response relationship between duration of breastfeeding and language skills and non-verbal intelligence. However, it is important to note that the association between the duration of breastfeeding and cognitive skills demonstrated in this study does not necessarily mean causation. Causation has to be confirmed through further research studying the mechanisms of how breastfeeding could enhance cognitive skill development.

Additionally, the positive effects of breastfeeding likely don’t continue forever (imagine drinking breastmilk in high school!). Research into an approximate age beyond which breastmilk has little additional benefit may help mothers like you estimate an appropriate age to wean their child. However, setting such a guideline may not be accurate for all children, because of differential genetic compositions and environmental exposures.

Furthermore, the duration of exclusive breastfeeding is not known in this study. The effect of duration of exclusive breastfeeding on cognitive function may be a useful topic for further research, to determine if the positive cognitive effects seen in this study is due to the intake of breastmilk in itself, or is only seen in exclusive breastfeeding.

What does this mean for me and my baby?

We know you cannot ignore practicality and your child’s unique needs. It may not be feasible to breastfeed your child for a long period of time for various reasons beyond generalisation, nor may it be necessary to do so. However, the current evidence shows that your baby may have greater language and non-verbal skills if they are breastfed for longer. This may translate into a good foundation for development, learning, and success later in life.

So when in doubt, breast is best.

 Please note: The World Health Organisation (WHO) recommends 6 months of exclusive breastfeeding, followed by breastmilk alongside complementary foods up to 2 years or beyond.

Please speak to your healthcare provider for breastfeeding or weaning advice to decide what is best for you and your child.

References:

Lovcevic I. Associations of breastfeeding duration and cognitive development from childhood to middle adolescence. Acta Paediatr. 2023;112:1696–1705. https://doi.org/10.1111/apa.16837 .

WHO. Infant and young child feeding [Internet]. 2023 [cited 2025 Jul 25]. Available from: https://www.who.int/news-room/fact-sheets/detail/infant-and-young-child-feeding .