Why breastfeed? A closer look at some of the evidence

In the USA, exclusive breastfeeding for the first 6 months of life is regarded as the best strategy for feeding a newborn, the other option being partial or complete formula feeding. The US Department of Health and Human services states the following reasons why breastfeeding is better for babies:

  • Milk adapts to the babies’ needs.
  • Breast milk is easier to digest than formula.
  • Breastfeeding protects infants from infectious and non-communicable disease. Infectious diseases include respiratory infections, and this protection is presumably from the antibodies in colostrum. The non-infectious diseases mention run the gamut from atopic dermatitis and asthma to childhood leukemia.

For mothers, breastfeeding also has the following benefits:

  • There is no formula to prepare or bottles to sterilise.
  • It is around $1500 per year cheaper than formula, and healthcare costs are lower because babies are sick less often.
  • It encourages bonding.
  • Mothers who have breastfed have a lower risk of some diseases like diabetes, breast and ovarian cancer, and postpartum depression.

Since I am a skeptic at heart, I decided to look more in-depth at the evidence behind the recommendations. I did a poor man’s literature review: I searched the well-known scientific journal database, Pubmed, to find the last five publications that investigated breastfeeding and the incidence of infections.

Paper 1: Exclusive breastfeeding protects against acute respiratory infections in Greek infants

The research group looked at the incidence of infectious episodes in 926 infants over their first year of life. 17% of the mothers still breastfed at 6 months.  There were almost 4000 episodes of an infectious illness recorded during the study, and 96% of infants had at least one episode. Infants exclusively breastfed for 6 months had a statistically significant reduction in the number of acute respiratory infections, 50% compared with 65%. There were also trends for reduced ear infections, gastroenteritis, conjunctivitis, thrush and any hospitalisation in their model. Bottom line: breastfeeding for 6 months was associated with fewer respiratory infections.

Paper 2: Breastfeeding reduces hospital admissions in the first six months of life for infants in Hong Kong

The researchers followed 8327 children for 8 years in a population study. They looked at children exclusively breastfed for the first 3 months of life. I don’t have access to the full paper via my university journal log in, so I can’t report on the rates of breastfeeding or disease in the group studied. The study showed that there was a statistically significant reduction in the number of hospitalisations for respiratory tract infections, and any infection, during the first 6 months of life. Bottom line: breastfeeding for 3 months was associated with fewer hospitalisations for any infection, and respiratory tract infection.

Paper 3: Breastfeeding reduces the risk of infections in Dutch infants

This third group of researchers had a cohort of 4164 infants as part of a larger study. 34% of mothers breastfed for 6 months. 48% of infants had a respiratory tract infection, and 8% had a gastrointestinal tract infection. Breastfeeding for at least 6 months was associated with a statistically significant reduced risk of both upper and lower respiratory tract infections and gastrointestinal tract infections according to their model. Infants breastfed for only 4 months or up to 6 months didn’t have this reduced risk. The associations were stronger for exclusive breastfeeding. Bottom line: Breastfeeding for 6 months+ reduced incidence of respiratory and gastrointestinal tract infections

Paper 4: Breastfeeding associated with reduced ear infections but not respiratory tract infections in Finnish infants

This fourth paper looked at 594 infants in childcare centers in Finland. It was cross-sectional rather than prospective like the previous three articles, so the researchers could only link prior breastfeeding with infections in children aged from 1 to 6 years. There was a highly statistically significant reduced incidence of recurrent  ear infections in children, but not with respiratory tract infections. Bottom line: Breastfeeding more than 6 months is associated with reduced ear infections in children aged 1 to 6

Paper 5: Formula-fed infants more likely to be hospitalised for infectious disease

Now a paper from the Philippines. This case-control study matched hospitalised infants with control infants and compared rates of breastfeeding. Infants who were hospitalised were on average 8 weeks old at the time of the study, compared to 10 weeks for the control group. Exclusive breastfeeding rates were similar at around 21% however 33% of the hospitalised infants were exclusively formula fed compared to only 15% of the control infants. Exclusively formula fed infants had a risk almost 4 times the rate of exclusively breastfed infants for any infection, and diarrhea. Bottom line: formula feeding is associated with increased infectious disease and diarrhea compared to breastfed infants

Summary: The latest scientific publications, chosen arbitrarily as the last five published in Pubmed, support the recommendation that breastfeeding reduces some infectious illnesses in infants.


1) Ladomenou F, Moschandreas J, Kafatos A, Tselentis Y, Galanakis E. Protective effect of exclusive breastfeeding against infections during infancy: a prospective study. Arch Dis Child. 2010 Sep 27.

2) Tarrant M, Kwok MK, Lam TH, Leung GM, Schooling CM. Breast-feeding and Childhood Hospitalizations for Infections. Epidemiology. 2010 Sep 22.

3) Duijts L, Jaddoe VW, Hofman A, Moll HA. Prolonged and exclusive breastfeeding reduces the risk of infectious diseases in infancy. Pediatrics. 2010 Jul;126(1):e18-25.

4) Hatakka K, Piirainen L, Pohjavuori S, Poussa T, Savilahti E, Korpela R. Factors associated with acute respiratory illness in day care children. Scand J Infect Dis. 2010 Sep;42(9):704-11.

5) Hengstermann S, Mantaring JB 3rd, Sobel HL, Borja VE, Basilio J, Iellamo AD, Nyunt-U S. Formula feeding is associated with increased hospital admissions due to infections among infants younger than 6 months in Manila, Philippines. J Hum Lact. 2010 Feb;26(1):19-25.

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