Maternal Vaginal Fluids Play A Major Role In The Colonization of The Neonatal Intestinal Microbiota

Background: Caesarean delivery (CD) is associated with newborns’ health risks due to the blocking of microbiome transfer. To understand the vertical bacterial seeding and reduce CD disadvantages, microbiome transmissions via anal and genital routes were investigated, and the efficiency of vaginal fluid swabbing treatment was evaluated using 16s rDNA sequencing-based techniques.Results: Pregnant women were recruited in the Women and Children’s Hospital, School of Medicine, Xiamen University from June 1st to August 15th, 2017. Maternal faeces (n = 26), maternal vaginal fluids (n = 26), and neonatal transitional stools (n = 26) were collected, while the participants underwent natural delivery (ND) (n = 6), CD (n = 4) and CD with vaginal fluid swabbing (CS) on their newborns (n = 16). 26 mothers with the median age 26.50 (25.00-27.25) years showed no substantial clinical differences. The newborns’ gut microbiota altered among ND, CD and CS, and clustered into two groups (PERMANOVA P < 0.01) of swabbing and no-swabbing exposure. Gut colonization of ND babies majorly originated from maternal vaginal microbes (PERMANOVA P = 0.08), no vertical transmission was observed via anal route in any group. The vaginal transfer partially occurred by swabbing, in which the phyla Firmicutes and Proteobacteria and the genera Lactobacillus, Bacteroides, and Escherichia-Shigella in newborns were similar to their mothers. The recovered taxa predicted KEGG functions of biosynthesis, metabolism, and DNA replication and repair with benefits of low risks of digestive, cardiovascular, and immune diseases.Conclusions: The newborn’s gut microbiota is mainly shaped by maternal vaginal microbiota, and aberrant colonization initiated by CD is partly mitigated by the swabbing treatment.