Is breastfeeding protective against the development of asthma or wheezing in children? A systematic review and meta-analysis

Methods Prospective cohort studies of preschool (4-6 years) and school-aged (7-9 years) children were identified from Medline (1948-June 2011) and Embase (1980-June 2011). Breastfeeding exposure for at least the first 3-4 months of life was defined as exclusive (breast milk as the only source of nutrition) or any (breast milk included in the diet). Outcomes were parent-reported PDA or wheezing. Risk of bias in included studies was assessed using the Newcastle-Ottawa scale. Data were analyzed using the Revman software package and adjusted odds ratios were meta-analyzed using random-effects models.