Protective effect of breastfeeding against obesity in childhood. Can a meta-analysis of observational studies help to validate the hypothesis?

The relationship between breast-feeding and childhood obesity is of great interest. Since 2000, sixteen studies have been published with conflicting data regarding the potential protective effect of breast-feeding on childhood obesity. A narrative review of Dewey in 2003 suggested a protective effect of breast-feeding, but an editorial in the British Medical Journal later that year cited two more recent studies without such an effect and stated there was inconclusive evidence A recent meta-analysis, however, has suggested a small, but significant, protective effect of breast-feeding. This paper summarizes this meta-analysis and discusses the strengths and limitations of the meta-analysis approach.