Importance of Breastfeeding

by Dr Clare Macdonald, General Practitioner  

Findings from epidemiology and biology studies substantiate the fact that the decision to not breastfeed a child has major long-term effects on the health, nutrition, and development of the child and on women’s health. Possibly no other health behaviour can affect such varied outcomes in the two individuals who are involved: the mother and the child.

Victora C.G. et al (2016) Lancet Breastfeeding Series                                         

There are defined differences in various health outcomes between mothers who breastfeed and those who formula feed as well as differing outcomes for their infants1. On a population level there is an increased risk of various pathologies affecting both mother and infant and these are well documented in the literature and exist across all demographics2. In general, the health risks associated with not breastfeeding are greatest when there is no breastfeeding at all, with gradually improving outcomes proportional to the duration and exclusivity of breastfeeding. In addition to the health risks associated with not breastfeeding there are wider, far reaching risks to society in terms of health and economic costs3, 4.

Of course, in some situations breastfeeding is medically contraindicated, or highly challenging due to personal or social problems and the risks associated with not breastfeeding should be considered in the context of each dyad.

Importance of Breastfeeding For the Infant

After millions of years of evolutionary refinement, human milk differs in composition from other mammalian milks. It is thought that the unique and species-specific immune and nutritional content of milks have arisen as a result of natural selection– allowing for optimal infant survival5.

From Public Health England & Unicef UK Baby Friendly Initiative: Infant Feeding- Commissioning Services, July 20166

Infants who are not breastfed are at increased risk of:

  • Respiratory and gastrointestinal infections: The link between higher rates of acute infection in non-breastfed infants has been long established. The effect appears to be ‘dose dependent’ with those breastfed exclusively, and for longer being the most protected7.
  • Sudden Infant Death Syndrome (SIDS): Breastfeeding is an independently protective factor with infants who have received no breastmilk being at highest risk (when other risk factors are adjusted)8.
  • Asthma: Infants who are not breastfed may experience higher rates of asthma and childhood wheeze9.
  • Type 2 diabetes: Breastfed infants are less likely to develop type 2 diabetes later in life, and additionally have been shown to have lower serum insulin concentrations in adulthood10.
  • Obesity: This association is probable, although further studies are needed. The available evidence suggests that breastfeeding is likely to confer some protection against childhood overweight and obesity in high income countries. The mechanism for this is likely to be multi-faceted– exclusive breastfeeding to 6 months precludes early introduction of complementary foods, breastmilk contains hormones which help regulate food intake, protein and total calorie intake are lower in breastfed infants and higher intake in infancy is associated with obesity later in childhood11.

Importance of Breastfeeding For the Mother

The risks to mothers of not breastfeeding are less well documented in the literature relative to the risks to infants12. However, evidence is available for multiple short and long term differences in health outcomes for mothers who breastfeed compared with those who don’t.

From Public Health England & Unicef UK Baby Friendly Initiative: Infant Feeding- Commissioning Services, July 20166

Mothers who do not breastfeed are at increased risk of:

  • Post-partum bleeding: The oxytocin release caused by breastfeeding causes uterine contraction; women who breastfeed therefore have less post-partum bleeding12.
  • Pre-menopausal breast cancer: Breastfeeding reduces the risk of pre-menopausal triple-negative breast cancer (TNBC). See our page ‘Breast Cancer Risk Reduction‘ for detailed information.
  • Ovarian cancer: Women who have breastfed for at least 12 months experience lower rates of ovarian cancer13.
  • Type 2 diabetes after gestational diabetes: With the greatest risk reduction being amongst women who breastfeed for longest and most exclusively14.
  • Postpartum Depression: Mothers who plan to and then are able to go on to breastfeed, have a reduced risk of postpartum depression, compared to mothers who plan to and proceed to artificially feed their babies15.

Additionally, lactational amenorrhoea provides a reduced pregnancy risk and can improve pregnancy spacing (see our page on ‘Family Planning’).

Societal and Economic Impact

The cost to society of the impact of not breastfeeding is estimated to be US $302 billion per year4. Increasing breastfeeding rates at 4 months to 45% in the UK could save US $29.5 million due to the protective effect of breastfeeding on childhood disorders4.

From Public Health England & Unicef UK Baby Friendly Initiative: Infant Feeding- Commissioning Services, July 20166

The Lancet Breastfeeding Series published in January 2016 is the largest and furthest reaching research into the effects of breastfeeding. It draws clear and strong conclusions that the scale of not breastfeeding has health and economic costs globally. It estimates that annually, around 823,000 deaths of under 5-year olds and 20,000 annual deaths from breast cancer3 could be prevented if breastfeeding was upscaled to reflect WHO guidance16.

Pre-dating the Lancet Papers, in 2012 Unicef UK commissioned a report into the cost and health impact of breastfeeding in the UK; ‘Preventing Disease and Saving Resources: the potential contribution of increasing breastfeeding rates in the UK17. This report highlighted the link between investment in breastfeeding support and subsequent reduction in hospital admissions in under 1-year olds with gastroenteritis.  The case study highlighted in Harrow showed that when multi-disciplinary training across midwives, health-visitors and GPs was rolled out in both hospital and community settings ‘women experienced a joined-up, consistent level of care’.

Modelling done by Unicef showed that if breastfeeding rates at 4 months were 45% and 75% of babies discharged from neonatal units were breastfed, there could be 53,930 fewer GP consultations annually for gastrointestinal illness, otitis media and lower respiratory tract infections.  The modelling also predicted 9,201 fewer hospital admissions and 361 fewer cases of NEC17. 

There are financial implications for families who are formula feeding with infant milks varying in cost around £1-4 per day for a typical infant aged 2-3 months18.  This does not take into account the additional cost of bottles and sterilising equipment. The impact of this may be most felt by low-income families, who in the UK are also less likely to breastfeed19.

Further Information

Acta Paediatrica: Special Issue- Impact of Breastfeeding on Maternal and Child Health  2015

Lancet Breastfeeding Series 2016

Evidently Cochrane: New Lancet Breastfeeding Series is a Call to Action 2016- Summarises the Lancet Breastfeeding Series

Unicef UK: Preventing Disease and Saving Resources- The Potential Contribution of Increasing Breastfeeding Rates in the UK 2012

Cancer Research UK: Not Breastfeeding and Preventable Cancers Cancer Research UK estimates that in the UK 1,500 breast cancer cases (3% of breast cancers) and 1,200 ovarian cancer cases per year (18% of ovarian cancers) were related to not breastfeeding in 2011.


  1. Stuebe A. The Risks of Not Breastfeeding for Mothers and Infants. Reviews in Obstetrics and Gynecology. 2009;2(4):222-231.
  2. Grummer-Strawn L, Rollins N. Summarising the health effects of breastfeeding. Acta Paediatrica. 2015;104:1-2.
  3. Victora C, Bahl R, Barros A, França G, Horton S, Krasevec J et al. Breastfeeding in the 21st century: epidemiology, mechanisms, and lifelong effect. Lancet. 2016;387(10017):475-490.
  4. Rollins N, Bhandari N, Hajeebhoy N, Horton S, Lutter C, Martines J et al. Why invest, and what it will take to improve breastfeeding practices?. Lancet. 2016;387(10017):491-504.
  5. Goldman A. Evolution of Immune Functions of the Mammary Gland and Protection of the Infant Breastfeeding Medicine. 2012;7(3):132-142.
  6. Public Health England: Infant Feeding- Commissioning Services July 2016
  7. WHO: Short Term Effects of Breastfeeding- A Systematic Review on the Benefits of Breastfeeding on Diarrhoea and Pneumonia Mortality 2013
  8. Hauck F, Thompson J, Tanabe K, Moon R, Vennemann M. Breastfeeding and Reduced Risk of Sudden Infant Death Syndrome: A Meta-analysis. Pediatrics. 2011;128(1):103-110.
  9. Dogaru C, Nyffenegger D, Pescatore A, Spycher B, Kuehni C. Breastfeeding and Childhood Asthma: Systematic Review and Meta-Analysis. American Journal of Epidemiology. 2014;179(10):1153-1167.
  10. Owen C, Martin R, Whincup P, Smith G, Cook D. Does breastfeeding influence risk of type 2 diabetes in later life? A quantitative analysis of published evidence. American Journal of Clinical Nutrition 2006 Nov;84(5):1043-54
  11. WHO: Exclusive breastfeeding to reduce the risk of childhood overweight and obesity September 2014
  12. Dieterich C, Felice J, O’Sullivan E, Rasmussen K. Breastfeeding and Health Outcomes for the Mother-Infant Dyad. Pediatric Clinics of North America. 2013;60(1):31-48.
  13. Ip S, Chung M, Raman G, Trikalinos T, Lau J. A Summary of the Agency for Healthcare Research and Quality’s Evidence Report on Breastfeeding in Developed Countries. Breastfeeding Medicine. 2009;4(s1):S-17-S-30.
  14. Gunderson EP, Hurston SR, Ning X, et al. Lactation and Progression to Type 2 Diabetes Mellitus After Gestational Diabetes Mellitus: A Prospective Cohort Study. Annals of Internal Medicine. 2015;163(12):889-898. doi:10.7326/M15-0807.
  15. Borra C, Iacovou M, Sevilla A. New Evidence on Breastfeeding and Postpartum Depression: The Importance of Understanding Women’s Intentions. Maternal and Child Health Journal. 2014;19(4):897-907.
  16. WHO Infant and Young Child Feeding Factsheet Updated September 2016
  17. Unicef UK: Preventing disease and saving resources- the potential contribution of increasing breastfeeding rates in the UK October 2012
  18. First Steps Nutrition Trust: Cost of Infant Milks Marketed in the UK June 2019, scroll down to the pink report
  19. Infant Feeding Survey 2010: Chapter 2- Incidence, Prevalence and Duration of Breastfeeding 

Published April 2017, Updated October 16th 2019