Delivery Mode and the Transition of Pioneering Gut-Microbiota Structure, Composition and Predicted Metabolic Function

Abstract

Cesarean (C-section) delivery, recently shown to cause excess weight gain in mice, perturbs human neonatal gut microbiota development due to the lack of natural mother-to-newborn transfer of microbes. Neonates excrete first the in-utero intestinal content (referred to as meconium) hours after birth, followed by intestinal contents reflective of extra-uterine exposure (referred to as transition stool) 2 to 3 days after birth. It is not clear when the effect of C-section on the neonatal gut microbiota emerges. We examined bacterial DNA in carefully-collected meconium, and the subsequent transitional stool, from 59 neonates [13 born by scheduled C-section and 46 born by vaginal delivery] in a private hospital in Brazil. Bacterial DNA was extracted, and the V4 region of the 16S rRNA gene was sequenced using the Illumina MiSeq (San Diego, CA, USA) platform. We found evidence of bacterial DNA in the majority of meconium samples in our study. The bacterial DNA structure (i.e., beta diversity) of meconium differed significantly from that of the transitional stool microbiota. There was a significant reduction in bacterial alpha diversity (e.g., number of observed bacterial species) and change in bacterial composition (e.g., reduced Proteobacteria) in the transition from meconium to stool. However, changes in predicted microbiota metabolic function from meconium to transitional stool were only observed in vaginally-delivered neonates. Within sample comparisons showed that delivery mode was significantly associated with bacterial structure, composition and predicted microbiota metabolic function in transitional-stool samples, but not in meconium samples. Specifically, compared to vaginally delivered neonates, the transitional stool of C-section delivered neonates had lower proportions of the genera Bacteroides, Parabacteroides and Clostridium. These differences led to C-section neonates having lower predicted abundance of microbial genes related to metabolism of amino and nucleotide sugars, and higher abundance of genes related to fatty-acid metabolism, amino-acid degradation and xenobiotics biodegradation. In summary, microbiota diversity was reduced in the transition from meconium to stool, and the association of delivery mode with microbiota structure, composition and predicted metabolic function was not observed until the passing of the transitional stool after meconium.

Lack of mucosal cholinergic innervation is associated with increased risk of enterocolitis in Hirschsprung’s disease

“…Interestingly, development of enterocolitis was significantly associated with cesarean delivery at birth of the infant in the prospective HSCR patient cohort. Microbial composition in children delivered by cesarean section is known to be associated with skin commensals such as Staphylococcus , while the microbiome in children delivered by natural birth mode is characterized by vaginal bacteria, e.g., Bifidobacteria and Lactobacillus 107–110 . However, since cesarean section was not a significant risk factor in the retrospective patient cohort, its role in enterocolitis development needs to be further examined.…”

Associations of birth mode with cord blood cytokines, white blood cells, and newborn intestinal bifidobacteria

“…Neonates delivered by pre-labor Cesarean section, on the other hand, miss out on this microbially-rich bath. High-throughput amplicon sequencing of bacterial DNA has shown that vaginally-delivered infants are colonized with organisms mainly from the mother's vaginal and intestinal microbiota, whereas Cesarean-delivered infants are colonized with skin and environmental microbiota [ 23 – 25 ]. Our findings are also consistent with other studies that have shown that compared to vaginally-delivered infants, Cesarean-delivered infants intestinal flora is characterized by a notable absence of Bifidobacterium spp .…”

An Overview of Gut Microbiota and Colon Diseases with a Focus on Adenomatous Colon Polyps

“…Maternal transmission can influence microbiota richness and diversity. Infants born by birth canal compared with those born by caesarean section delivery show a greater microbial diversity [ 139 ]. Nursing as well as skin and oral contact with the mother influence maternal transmission.…”