The researchers of this new study, which was the largest ever and involved 5,475 children and their mothers in the USA, re-examined the effect of breastfeeding whilst taking into account the IQ of the mothers. Comparison was also made between siblings within the sample who were not breastfed.
When taken in isolation, the results of the study seemed to indicate that breastfeeding had a beneficial effect on the child’s intelligence. However, when other factors were considered – maternal intelligence, home environment and socio-economic status - breastfeeding made less than half a point difference to the children’s intelligence scores.
Re-analysis of the data with maternal intelligence omitted showed that the effects of breastfeeding were at least double. This result highlighted that failing to take in to account the mother’s intelligence can overestimate the effects of breastfeeding.
The authors emphasise that breastfeeding remains important for healthy growth and development in infants, and has advantages for the mother and the child.