Vaginal Microbiome Seeding and Health Outcomes in Cesarean-delivered Neonates: a Randomized Controlled Trial

Cesarean section (CS) delivery is a common surgical procedure intended to increase the chances of successful delivery and to protect the health of the mother and baby. Yet this intervention is overused and has been associated with higher risk of immune and metabolic disorders in the offspring. It is hypothesized that these associations are due to CS-delivered newborns not receiving the full inoculum of maternal microbes at birth.

While restoring labor is not possible, restoring the microbes that colonize infants during birth through exposure to vaginal flora, is feasible, and has been shown in a small pilot study, to normalize the microbiota of the intestine, skin and mouth during the first month of life.

The investigators hypothesize that the restoration of the vaginal microbiota to the infant at birth will restore the infant microbiome and decrease the risk of obesity and other immune-mediated diseases linked with CS. The investigators aim to test this hypothesis in a randomized controlled trial by first examining the effect of vaginal seeding, in CS-delivered newborns, on the gut microbiota composition, structure and function (Phase I of study; first 50 infants) and then on the BMI z score and other immune-mediated outcomes (Phase II of study; 600 infants).

Methods: CS-delivered neonates will be randomized to either an experimental arm with exposure to the maternal vaginal microbiota at birth, or a control arm with no exposure. Feces, skin, saliva, breast milk, and vaginal swabs will be collected for microbiome analysis. The investigators will obtain clinical information from in-person visits, surveys and the electronic health record.

Implications: this randomized controlled clinical study will provide evidence of whether the "vaginal seeding" procedure can safely transfer microbes from mom-to-baby, and whether these microbes are beneficial for the metabolic and immune health of the child.