To evaluate the establishment of gut microbiota in children born by vaginal versus caesarean delivery and its impact on mucosal immunity.
165 consecutive children were followed from birth, 141 (85%) born by vaginal delivery and 24 (15%) by caesarean section. Infants exposed to probiotics directly or through the mother were excluded. Enzyme-linked immunospot (ELISPOT) assay was used for indirect evaluation of mucosal immunity and fluorescence in situ hybridization of bacterial cells (FISH) for determination of the gut microbiota.
At 1 month of age, the total gut bacterial cell counts were higher in vaginally delivered infants (9.9E9, 95% CI 7.9E9-1.2E10) as compared to caesarean delivered (3.1E9, 1.1E9-8.6E9) (p = 0.001). This distinction was due to the greater number of bifidobacteria in vaginally delivered infants (1.9E9, 95% CI 6.3E8-5.6E9 versus 1.5E6, 95% CI 4.1E2-5.7E9), (p = 0.001), but not the numbers of Clostridia, Lactobacilli or Bacteroides. During the first year of life, the number of total IgA-secreting cells was lower (p = 0.03) in infants born by vaginal versus caesarean delivery, possibly reflecting excessive antigen exposure across the vulnerable gut barrier resulting from inadequate development of the gut microbiota.
A significant correlation between the mode of delivery, gut microbiota and mucosal immunity was detected.
The mode of delivery has, via gut microbiota development, significant effects on immunological defence in the infant.