Breastfeeding And IQ – The Facts
Cognitive development refers to growth in a range of thinking and learning skills – language, attention, planning, problem solving and memory.
IQ is a measure of cognitive ability.
There is a substantial amount of research demonstrating the importance of breastfeeding for optimal cognitive development and, therefore, IQ.
Breastfeeding is the biologically normal way to feed babies. It's hardly surprising then that breastfeeding is important for cognitive development and IQ.
Just because other factors influence IQ (or might even have a greater influence than breastfeeding), it doesn’t mean breastfeeding has no role in cognitive development.
So, what differences, in terms of cognitive development, are seen between babies who are breastfed and those who are not?
What does the research really reveal, and how does breastfeeding assist cognitive development?
Breastfeeding And IQ: Brain Structure
Research has found breastfeeding supports the growth and development of white matter in the brain. White matter assists with fast and organised brain functioning. It’s mainly made of myelin, which surrounds nerves. Myelin ensures signals travel quickly and efficiently along nerves.
Brain imaging scans of children aged between 10 months and 4 years found children who were formula fed showed less white matter development than those who were mixed fed.
Also, those who were mixed fed showed less white matter development than those who were exclusively breastfed for at least 3 months.
The Latest Research
Many research papers report ways in which breastfeeding reduces risk, rather than how lack of breastfeeding increases risk. Therefore, some of the research results in this article are presented in the way the research papers present it.
However, since breastfeeding is the biologically normal way to feed babies, it really should be the control or the benchmark with which other forms of infant feeding are compared. So, rather than referring to benefits of breastfeeding, and how breastfeeding lowers the risk of X, Y or Z, there should be focus on the risks of not breastfeeding, and how not breastfeeding increases the risk of X, Y or Z.
When good quality observational studies (those that takes into account relevant confounding factors) are combined and analysed, a consistent and significant difference between IQ scores of breastfed and formula-fed babies has been found, with formula-fed babies having IQs 3.45 points lower, on average, than IQs t of breastfed babies.
More recently, two large prospective studies (where a group of individuals is followed over a period of time) have been done.
Firstly, a large prospective study in the United States looked at breastfeeding duration and exclusivity, and assessed the relationship with cognitive development and IQ, in children at three, and at seven years of age. For children aged seven, any breastfeeding to 12 months led to an increase of 0.35 verbal IQ points, and 0.29 nonverbal IQ points. Exclusive breastfeeding to 6 months led to an increase of 0.80 verbal IQ points and 0.58 nonverbal IQ points.
Secondly, in another large prospective study in Brazil, participants who had been breastfed for 12 months or more had higher IQ scores (3·76 points), completed more years of education (0·91 years), and had higher monthly incomes (341 Brazilian reals) than did those who were breastfed for less than 1 month.
There has been a small number of experimental studies done to look at the relationship between breastfeeding and IQ. Experimental studies minimise confounding factors that might influence breastfeeding practices.
In the 1980s, more mothers made the decision not to express and provide their expressed breastmilk (EBM) to their premature babies. This enabled a randomised controlled trial in the UK to be undertaken. In this study, premature babies of mothers who chose not to provide them with their EBM were randomly assigned to receive either a standard term formula or a preterm formula. Babies of mothers who chose to provide them with EBM were randomly allocated to receive term or preterm formula as a supplement to their EBM.
The study found children who received none of their mother’s EBM in the early weeks of life had, at 7 ½-8 years of age, a significantly (8.3 points) lower IQ than those who received their mother’s EBM. A dose response relationship was also found in that the less EBM (or more formula) babies received, the lower their subsequent IQs.
Another large cluster randomised controlled trial of a breastfeeding intervention in Belarus found that the group that didn’t receive the breastfeeding intervention (and had lower rates of breastfeeding) had a lower IQ (by 5.9 points) at 6½ years of age than the group that did receive the breastfeeding intervention (and had higher rates of breastfeeding).
Long-chain fatty acids (namely docosahexaenoic, DHA, and arachidonic, AA, acids) in breastmilk are thought to be a factor in the way breastfeeding influences cognitive development. These fatty acids make up 20% of the fatty acid content of the brain and are important for nerve growth, repair, and myelination (the process by which myelin surrounds nerves).
It’s important to note, however, that it's unlikely to be any one factor (or one group of factors) in breastmilk that influences cognitive development. All factors in breastmilk are part of a system, and they all work, if not in unison, to support a baby’s growth and development. See a list of all the ingredients in breastmilk and formula.
Interaction Between Mothers And Their Babies
The act of breastfeeding itself can influence a child’s cognitive development.
Breastfeeding allows frequent closeness and interaction between a mother and her baby. Because breastfed babies typically feed from both breasts, this means a baby’s alternate visual fields are used. These things can influence a baby’s brain development.
There are things in the information above that mothers who bottle feed their babies can replicate. Find out more about bottle nursing.
The above information can sound like a good news story for breastfeeding mums and a bad news story for formula feeding mothers. But people deserve to be fully informed. And, in the end, when it comes to our own children, we each choose what works best. Research like this is important for the general population, but as individuals we must make up our own minds as to how relevant it is for us.