Breastfeeding and asthma and allergies: a systematic review and meta-analysis

AimTo systematically review the association between breastfeeding and childhood allergic disease. MethodsPredetermined inclusion/exclusion criteria identified 89 articles from PubMed, CINAHL and EMBASE databases. Meta-analyses performed for categories of breastfeeding and allergic outcomes. Meta-regression explored heterogeneity. ResultsMore vs. less breastfeeding (duration) was associated with reduced risk of asthma for children (5-18years), particularly in medium-/low-income countries and with reduced risk of allergic rhinitis 5years, but this estimate had high heterogeneity and low quality. Exclusive breastfeeding for 3-4months was associated with reduced risk of eczema 2years (estimate principally from cross-sectional studies of low methodological quality). No association found between breastfeeding and food allergy (estimate had high heterogeneity and low quality). Meta-regression found differences between study outcomes may be attributable to length of breastfeeding recall, study design, country income and date of study inception. Some of the protective effect of breastfeeding for asthma may be related to recall bias in studies of lesser methodological quality. ConclusionThere is some evidence that breastfeeding is protective for asthma (5-18years). There is weaker evidence for a protective effect for eczema 2years and allergic rhinitis 5years of age, with greater protection for asthma and eczema in low-income countries.