On the 12 October, the Institute of Social and Economic Research (ISER) held a policy discussion called Early Intervention and Social Mobility: Are pro-breastfeeding policies worth it?

The event was held to present research findings related to The effects of breastfeeding on children, mothers and employers - a £240,000 project funded by the Economic and Social Research Council and conducted by researchers at the ISER and the University of Oxford. Data from the Millennium Cohort Study, the National Sentinel Caesarean Section Audit, the Avon Longitudinal Study of Parents and Children and the Baby Friendly Initiative, some of which has been reported previously, was used.

The research programme was presented under four main projects:

The Success Story of the UNICEF UK Baby Friendly Initiative

This aim of this project was to explore “whether there was a true causal link between breastfeeding and positive health, cognition and behavioural outcomes for the child”.

The research found that

  • Mothers giving birth in hospitals where Baby Friendly policies are fully implemented are 14.6% more likely to initiate breastfeeding and 6.6% more likely to continue to breastfeed exclusively at four weeks of age, in comparison to similar mothers in other hospitals.
  • These effects are stronger for less educated and more economically disadvantaged mothers.

Breastfeeding and infant hospitalisations for infections

The aim of this study was to measure the effect of breastfeeding on hospitalisation for diarrhoeal and lower respiratory tract infections in the first eight months after birth in the United Kingdom.

The study found that:

  • Exclusive breastfeeding, compared with not breastfeeding, protects against hospitalisation for diarrhoea and lower respiratory tract infection.
  • An estimated 53% of diarrhoea hospitalisations could have been prevented each month by exclusive breastfeeding and 31% by partial breastfeeding.
  • Similarly, 27% of lower respiratory tract infection hospitalisations could have been prevented each month by exclusive breastfeeding and 25% by partial breastfeeding.
  • The protective effect of breastfeeding for these illnesses wears off soon after breastfeeding stops.

Breastfeeding and socio-emotional development

The aim of this research was to find out if there is any association between breastfeeding and a child’s behaviour at age five years.

Results showed that:

  • 6% of full-term children breastfed for at least four months had parent reported behavioural problems, in comparison to 16% of formula-fed babies.
  • This lower risk of a full-term breastfed child having abnormal scores for behaviour remained even when researchers took into account other influences such as socioeconomic or parental factors.

Breastfeeding and cognitive development

The research examines 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.

The data was analysed using a technique that involves “twinning” each breastfed baby with one or more babies who were not breastfed, but who in all other observable respects are similar to the breastfed baby. By doing this, the researcher attempts to identify the “true” effect of breastfeeding on children’s cognitive development.

The research found that:

  • Breastfeeding has an effect on a child’s cognitive outcomes that cannot be entirely explained by a mother’s socio-economic background.
  • Controlling for a wide range of factors, children breastfed for four weeks or more do 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 is found across English, maths and science scores, and it persists at least until age 14.


Collectively, the results from ISER’s research point to the existence of some positive breastfeeding effects independent from other influencing factors such as social class or parents’ education. These results show that breastfeeding may well have a significant part to play in the Government’s efforts to reduce inequality.

The research also showed that the extent of time a child was breastfed was an important element in identifying a causal relationship between better child outcomes and breastfeeding – “It could be that only prolonged and exclusive breastfeeding (four months or longer) offers a substantial level of benefit.” This reiterates the importance of support for women to continue to breastfeed exclusively for longer.

To find out more about the research, visit ISER’s website.