Research Questions Link Between Breastfeeding and Child Intelligence

Child Intelligence and Breastfeeding

Breastfeeding has little or no effect on a child's intelligence, finds a BMJ study.

The link between breastfeeding and children's intelligence has been studied since 1929, but the relationship between the two remains unclear. Many of the studies that have found a link between breastfeeding and increased child intelligence have failed to consider other factors, particularly maternal intelligence. Researchers from the Medical Research Council Social and Public Health Sciences Unit in Glasgow, undertook the largest ever study " involving 5,475 children and their mothers in the USA " to re-examine the effect of breastfeeding taking into account maternal intelligence and other aspects of the child's background.

The findings showed that when considered in isolation, breastfeeding did appear to have a beneficial effect on a child's intelligence. However, once other factors were considered " including maternal intelligence, home environment and socio-economic status - breastfeeding made less than half a point difference to children's intelligence scores. When the data were re-analysed, and maternal intelligence omitted, the effects of breastfeeding were at least double that when tested with maternal intelligence " highlighting the fact that failing to take into account mothers' intelligence can 'seriously overestimate the effects of breastfeeding'.

The research also compared the data on siblings within the sample group " one of whom had been breastfed and another who had not " and this supported the finding. There was no significant difference between the intelligence of the child who had been breastfed and the child who had not.

An increase of one standard deviation (15 points) in a mother's intelligence score more than doubled the odds the child would be breastfed. According to the data, mothers who breastfed were also more likely to be older, to have more education and to provide a more stimulating home environment. They were less likely to be in poverty or to smoke.

The authors note their 'surprise' at the fact that maternal intelligence has been overlooked as a factor in other research, 'given the heritability of intelligence and the known association of maternal intelligence with both the initiation and duration of breastfeeding.' They conclude that whilst breastfeeding does not enhance child intelligence, it remains important for the healthy growth and development of infants and has many advantages for both mother and child.