Exclusive breastfeeding and incident atopic dermatitis in childhood: A systematic review and meta-analysis of prospective cohort studies

Background Breastfeeding is undisputedly preferable to formula feeding for infant nutrition because of its nutritional, immunological and psychological benefits. However, studies on the association between breastfeeding and development of atopic dermatitis (AD) have shown inconsistent results. Objectives To examine the association between exclusive breastfeeding for at least 3 months after birth and the development of AD in childhood. Methods An electronic literature search of MEDLINE (January 1966-May 2008) and EMBASE (1980-May 2008) was conducted. Prospective cohort studies that met the predetermined criteria were independently assessed by three reviewers. The pooled effect estimate was calculated by random effects model. Heterogeneity across the studies was investigated by meta-regression analysis. Results Twenty-one studies with 27 study populations were included for metaanalysis. The summary odds ratio (OR) for the effect of exclusive breastfeeding on the risk of AD was 0 89 (95% confidence interval, CI 0 76-1 04). Heterogeneity was found across the studies (v2 = 83 6, d.f. = 26; P <0 001). Breastfeeding was associated with a decreased risk of AD (OR 0 70; 95% CI 0 50-0 99) when analysis was restricted to the studies comparing breastfeeding with conventional formula feeding. The pooled OR for study populations with atopic heredity was 0 78 (95% CI 0 58-1 05). Conclusions There is no strong evidence of a protective effect of exclusive reastfeeding for at least 3 months against AD, even among children with a positive family history.