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.

Babies who are not breastfed are more likely to need medical attention or hospitalisation for respiratory illnesses than those who are breastfed.

A systematic review (Bachrach et al 2003) 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.

The nine studies included in the meta-analysis were:

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