Research on the links between breastfeeding and cognitive development
Impact of breastfeeding on intelligence, educational attainment and income at 30 years of age in Brazil
This prospective, population-based birth cohort study assessed whether breastfeeding duration was associated with IQ, years of schooling, and income at the age of 30 years, in a setting where no strong social patterning of breastfeeding exists.
The authors found that durations of total breastfeeding and predominant breastfeeding were positively associated with IQ, educational attainment, and income. They also identified dose-response associations with breastfeeding duration for IQ and educational attainment. Participants who were breastfed for 12 months or more had higher IQ scores, more years of education and higher monthly incomes than did those who were breastfed for less than 1 month. The results of this mediation analysis suggested that IQ was responsible for 72% of the effect on income.
The authors conclude that breastfeeding is associated with improved performance in intelligence tests 30 years later, and might have an important effect in real life, by increasing educational attainment and income in adulthood.
Victora et al (2015). Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil. Lancet Glob Health, 3: e199–205
- This is a ground-breaking study builds upon previous research as it links breastfeeding with improved cognitive, economic and social outcomes into adulthood
- The results of this study are particularly important as the study design (prospective, population-based) means that the findings are likely to be robust
- This study was carried out in Brazil during the 1980s when mothers from all social classes breastfed, so socioeconomic biases sometimes found in breastfeeding studies were absent in this case
- It is unclear whether the effects noted in this study result from the nutritional content of breastmilk itself, or the nurturing behaviours breastfeeding encourages, or a combination of both of these.
Breastfeeding and intelligence
This study systematically reviewed evidence of the association between breastfeeding and performance in intelligence tests. It was found that breastfeeding is related to improved performance in intelligence tests.
Horta, B. L. et al (2015). Breastfeeding and intelligence: a systematic review and meta-analysis. Acta Paediatrica, Special Issue: Impact of Breastfeeding on Maternal and Child Health. Volume 104, Issue Supplement S467, pages 14-19.
Impact of Baby Friendly accreditation on breastfeeding rates, cognitive outcomes and maternal mental health
Using data from the UK Millennium Cohort Study, these researchers found that women giving birth in hospitals that participated in the Baby Friendly Initiative (BFI) were up to 15 percentage points more likely to initiate breastfeeding and between 8 and 9 percentage points more likely to breastfeed exclusively at 4 and 8 weeks than comparable mothers giving birth in non-participating hospitals. Mothers from low income families, and with low levels of education, were more responsive to the BFI programme than highly educated mothers in more affluent families.
They then compared the outcomes of children who were breastfed as a result of the BFI program with those of otherwise similar non-breastfed children. They found significant effects of breastfeeding on cognitive outcomes throughout childhood, and in particular between ages 3 and 7. In contrast to the previous literature, researchers found no statistically significant impact of breastfeeding on a number of health outcomes, but saw an improvement in child emotional development and maternal mental health.
Breastfeeding and child development outcomes
This study investigated whether the nurturing hypothesis – that breastfeeding serves as a proxy for family socio-economic characteristics and parenting behaviours – accounts for the association of breastfeeding with children’s academic abilities. Results from the study suggested that breastfeeding may not be a proxy of socio-economic characteristics and parenting behaviours, as proposed by the nurturing hypothesis. The mechanism of breastfeeding benefits is likely to be different from those by which family socio-economic background and parenting practices exert their effects. The authors call for greater clarity in understanding the mechanisms behind breastfeeding benefits, to facilitate the development of policies and programs that maximise breastfeeding’s impact.
Long-chain polyunsaturated fatty acids (LC-PUFA) in colostrum, and infant mental development
This Spanish study of 657 pregnant women during pregnancy and 504 of their children at 14 months found that a high percentage of breastfeeds during the first 14 months was positively associated with child mental development. Maternal education, social class, and IQ only partly explained this association. LC-PUFA levels seem to play a beneficial role in children’s mental development when breastfeeding levels are high.
Guxens M, Mendez MA, Molto-Puigmarti C et al (2011) Breastfeeding, Long-Chain Polyunsaturated Fatty Acids in Colostrum, and Infant Mental Development. Pediatrics. Published online doi: 10.1542/peds.2010-1633
Breastfeeding and reduced risk of epilepsy
An observational study of 69,750 infants born in Denmark found that breastfeeding may decrease epilepsy in childhood. Researchers observed a dose-response like pattern; for example, children breastfed for 3 to 5, 6 to 8, 9 to 12, and >13 months had a 26%, 39%, 50%, and 59% lower risk of epilepsy after the first year of life, respectively, compared with children who were breastfed for <1 month.
Breastfeeding associated with higher test scores at age 9
This Irish study of 8,226 9 year-old children explored the impact of breastfeeding on educational test scores. After confounding for a range of child, maternal, socio-economic and socio-environmental factors, children who were breastfed were found to have a 3.24 percentage point advantage on reading scores and a 2.23 percentage point advantage on mathematics scores using standardised reading and mathematics tests. Any amount of breastfeeding was associated with significantly higher test scores than no exposure, but evidence of a dose-response relationship was weak.
The effect of breastfeeding on children’s cognitive development
This research examined the effect of breastfeeding on children’s cognitive outcomes, as measured by test scores in reading, writing and mathematics measured at ages 5, 7, 11, and 14. Authors found that breastfeeding had an effect on a child’s cognitive outcomes that could not be entirely explained by a mother’s socio-economic background. Controlling for a wide range of factors, children breastfed for four weeks or more did better than children breastfed for less than four weeks by about one tenth of a standard deviation (slightly less at younger ages, and slightly more at older ages). This loosely translates to a difference of about 3 IQ points. The effect was found across English, maths and science scores, and it persists at least until age 14.
Breastfeeding and academic achievement at 10 years
This Australian study of 1,038 children found that 10-year-old children who were predominantly breastfed for 6 months or longer in infancy had higher academic scores than children who were breastfed for less than 6 months. The effect of breastfeeding on educational outcomes differed according to gender; boys were particularly responsive (in mathematics, spelling, reading, and writing) to a longer duration of breastfeeding.
Wendy H Oddy, Jianghong Li, Andrew J O Whitehouse, Stephen R Zubrick, and Eva Malacova (2010) Breastfeeding Duration and Academic Achievement at 10 Years. Pediatrics, Dec 2010; doi:10.1542/peds.2009-3489
Breastfeeding is associated with improved child cognitive development: evidence from the UK Millennium Cohort Study
A total of 11,801 children were assessed according to their gestational age at birth and also according to breastfeeding status. At age five the children were tested using a validated tool – the British Ability Scales (BAS) test. The researchers found that the mean BAS naming vocabulary score decreased with prematurity. After adjusting for confounders, ever breastfeeding was significantly associated with a higher mean BAS naming vocabulary score in children born at term with a stronger effect in children born moderately preterm or very preterm and this also increased with each additional month of breastfeeding. A similar effect of breastfeeding was observed when using other BAS tests such as pattern construction and picture similarities scales.
Quigley MA, Hockley C, Carson C et al (2009) Breastfeeding is associated with improved child cognitive development: evidence from the UK Millennium Cohort Study. J Epidemiol Community Health; 63(Suppl_2):8
Breastfeeding and child cognitive development
A Belarusian Promotion of Breastfeeding Intervention Trial (PROBIT) study followed up 13,889 children from its original cohort at 6.5 years of age to assess whether prolonged and exclusive breastfeeding improves children’s cognitive ability. The researchers measured IQ scores and teacher evaluations of academic performance in reading, writing, mathematics, and other subjects. The experimental intervention led to a large increase in exclusive breastfeeding at age three months and a significantly higher prevalence of any breastfeeding at all ages up to and including 12 months. The experimental group had higher mean scores on all of the Wechsler Abbreviated Scales of Intelligence measures for IQ. Teachers’ academic ratings were significantly higher in the experimental group for both reading and writing. The researchers conclude that their results demonstrate that prolonged and exclusive breastfeeding improves children’s cognitive development.
Evidence confirms breastfeeding link to higher IQ
A team of scientists have looked at the DNA profile of more than 3,000 children involved in two long-term studies in the UK and New Zealand (NZ). In the UK, the study had followed a group of over 2,000 twins with IQ measured at age 5, whereas in New Zealand 1,037 children were studied, with IQ measured every other year from age 7-13. The researchers were able to eliminate a series of confounding variables which have been considered to impact upon intellectual development: intrauterine growth, social class and maternal cognitive ability. The retention rates were very high at 97% and 96% respectively.
The study found that in the presence of a particular gene in the child, FADS2, breastfeeding can raise IQ by an average of 7 points. FADS2 is closely involved in the way the body processes fatty acids in the diet and has two genotypes – C and G. Some 90% of people carry the C version of the gene, which the scientists found was associated with better IQ scores in breastfed children. Breastfeeding had no effect on the IQ of the 10% of children who had G versions of the gene; however their outcomes were made no worse by breastfeeding.