Possible Confounding Factors in an Oral Probiotics Trial: Breast Milk

We read with interest the Pediatrics article “Oral Probiotics Reduce the Incidence and Severity of Necrotizing Enterocolitis in Very Low Birth Weight Infants” by Lin et al.¹  However, an important confounding factor, ie, bacterial counts in breast milk, was not analyzed. Previous reports showed that bacteria in expressed breast milk (EBM) were associated with necrotizing enterocolitis and sepsis.^2,3  We reported previously that the bacterial colonization rate in EBM was high in Hong Kong.⁴  As a Chinese society, Taiwan may share a similar cultural belief that, we believed, accounted for the high bacterial colonization rate in Hong Kong. In their study, both EBM and banked breast milk, which usually was pasteurized,⁵  were treated as similar despite the fact that they were very different. It is important to analyze the proportion of EBM versus banked breast milk as the second confounding factor in the Lin et...