Robust evidence exists for the increased incidence of respiratory infections amongst term and moderately pre-term babies who are not breastfed. Amongst those who are breastfed, some studies have shown a “dose response” with both the duration and the exclusivity of breastfeeding affecting the incidence. Larger studies are more likely to show the effects of partial breastfeeding than smaller studies. See also Unicef UK’s report, Preventing disease and saving resources.
Breastfeeding reduces the risk of infectious diseases in infancy
This study of 4,164 infants in Holland found that exclusive breastfeeding for four months and partially thereafter reduced the risk of infections in the upper respiratory, lower respiratory and gastrointestinal tracts. Duijts L, Jaddoe VWV, Hofman A et al (2010) Prolonged and Exclusive Breastfeeding Reduces the Risk of Infectious Diseases in Infancy. Pediatrics; 126: e18-e25
Breastfeeding protection against diarrhoea and lower respiratory tract infection
This study of 18,819 infants found that exclusive breastfeeding protects against hospitalisation for diarrhoea and lower respiratory tract infection. The effect of partial breastfeeding is weaker. The findings suggest that an estimated 53% of diarrhoea hospitalisations could have been prevented each month by exclusive breastfeeding and 31% by partial breastfeeding. Similarly, 27% of hospitalisations for lower respiratory tract infection could have been prevented each month by exclusive breastfeeding and 25% by partial breastfeeding. Quigley M.A., Kelly Y.J., Sacker A.S. (2007) Breastfeeding and Hospitalization for Diarrheal and Respiratory Infection in the United Kingdom Millennium Cohort Study. Pediatrics; 119; e837- e842
A systematic review (Bachrach et al 2003)
This found 9 studies (out of 33 studies that met the primary inclusion criteria), in which the population had high standards of living and all the babies were initially well and term. A meta- analysis of these studies found more than a tripling in severe respiratory tract illnesses resulting in hospitalizations for infant who were not breastfed compared with those who were exclusively breastfed for 4 months, after controlling for socioeconomic factors and smoking.
Exclusive breastfeeding reduces the risk of respiratory illness
A meta-analysis of studies from developed countries has concluded that the risk of severe respiratory tract illness resulting in hospitalisation is more than tripled among infants who are not breastfed, compared with those who are exclusively breastfed for 4 months (relative risk = 0.28; 95% CI 0.14 – 0.54).
Early cessation of breastfeeding significantly increases the risk of respiratory illness
A study of 2602 children in Australia has found that hospital, doctor, or clinic visits and hospital admissions for respiratory illness and infection in the first year of life are significantly lower among babies who are predominantly breasfed. Stopping predominant breastfeeding before six months and stopping breastfeeding before eight months were associated with a significantly increased risk of wheezing lower respiratory illnesses. Upper respiratory tract infections were significantly more common if predominant breastfeeding was stopped before 2 months or partial breastfeeding was stopped before 6 months.
Oddy WH et al (2003). Breast feeding and respiratory morbidity in infancy: a birth cohort study. Archives of Disease in Childhood 88:224-228 [Abstract]
Exclusive breastfeeding reduces risk of respiratory infections, wheeze, excessive weight and high blood pressure
This study found that bottle-fed infants were at almost twice the risk of developing respiratory illness at any time during the first 7 years of life compared with breastfed infants. It also found that solid feeding before 15 weeks was associated with an increased probability of wheeze during childhood as well as increased percentage body fat and weight in childhood. Systolic blood pressure was raised significantly in children who were exclusively bottle fed compared with children who received breastmilk.