Vaginal Microbes Can Be Partially Restored To C Section Babies

    In a small pilot study, researchers at University of California, San Diego School of Medicine and Icahn School of Medicine at Mount Sinai determined that a simple swab to transfer vaginal microbes from a mother to her C-section-delivered newborn can alter the baby’s microbial makeup (microbiome) in a way that more closely resembles the microbiome of a vaginally delivered baby.

    By swabbing newborns with a gauze containing vaginal fluids from their mothers, and later testing samples collected from these newborns and their mothers using genomic technology and computational methods, the scientists showed that C-section infants became enriched in vaginal bacteria that were nearly absent in untreated infants. The researchers, which included a multi-center team and collaborators from NYU Langone Medical Center, published their study (“Partial restoration of the microbiota of cesarean-born infants via vaginal microbial transfer”) in Nature Medicine.

    Although C-sections are often a life-saving procedure for mothers and infants, this procedure comes with undesirable side effects for the newborn, including an increased risk for immune and metabolic conditions. This risk has been attributed to the aberrant microbiome found in newborns delivered via C-section, resulting from their lack of exposure to maternal vaginal microbes. The human microbiome encompasses the trillions of bacteria harbored in the body that are essential to our well-being.

    “There is a clear association between C-section and increased risk for several diseases,” said senior author of the study Jose C. Clemente, Ph.D., assistant professor of genetics and genomics and a member of the Icahn Institute at the Icahn School of Medicine at Mount Sinai, “but to date, only a few research studies in mice have demonstrated that this is caused by difference in the microbiome early in life. Our work is the first to demonstrate in humans that we can modify the abnormal bacterial communities found in C-section babies.”

    Over 1,500 samples were collected at multiple time points from several body sites of the infants and their mothers during the first month of life. The research team harnessed recent advances in DNA sequencing and big data analytics to characterize, for the first time, the microbial communities found in the infants delivered vaginally and by C-section. Analysis of these results determined that C-section infants exposed to their maternal vaginal fluids had a microbiome enriched in bacteria commonly found in vaginally delivered babies, including Lactobacillus and Bacteroides. These bacteria, nearly absent in C-section children that were not swabbed, have been linked to the proper development of the immune system and could provide an explanation for the lowered disease risks associated with vaginal delivery.

    “This study has allowed us to demonstrate the feasibility of bacterial restoration in a small cohort, but we do not know yet whether this procedure alone is sufficient to restore the health benefits associated with vaginal delivery,” said Dr. Clemente. “Studies that target children at risk for immune disorders, such as allergies, will be required to determine how microbial restoration affects health outcomes.”