Composition in phyla from breast milk: Effect of the mode of delivery

Breast milk is considered as a living ecosystem. Maternal, environmental and neonatal factors affect milk bacterial composition. The aim of present study was to assess the phyla from breast milk of mothers with vaginal delivery compared to the cesarean section. In this single-center case-control study, sixty women were participated. Half of them had vaginal delivery and others experienced cesarean section. The breast milk samples were collected three months after delivery for the DNA extraction to measure Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria using quantitative real time chain polymerase reaction. Daily intake of calories, protein, fat, carbohydrate and fiber did not differ significantly between the two groups. The proportion of Bacteroidetes, Firmicutes and Proteobacteria were significantly higher in milk of mothers with a cesarean section than the vaginal delivery (p=0.03, p=0.02 and p=0.042). Similarly, the Firmicutes to Bacteroides ratio was significantly increased (p=0.02). The Actinobacteria population was significantly higher in milk of vaginally-delivered mothers who had male infant than females (p=0.015). Breast milk of mothers with cesarean section showed alterations in the main bacterial phyla population compared to the vaginal delivery. Moreover, our results suggest that the sex of infant is an effective factor on some phyla quantity.