Characterization of newborn gut microbiota according to the pre-gestational maternal nutritional status and delivery mode.

Purpose: The aim of this study is to characterize the composition of the newborn gut microbiota based on the maternal pre-pregnancy nutritional status and the delivery mode.

Methods: A biological sample was collected from the anal mucosa of the newborns between 24 and 48 h after delivery, as it was not possible to collect a meconium sample at that time. A general data collection questionnaire was administered. The microbiome of the samples was analyzed by next-generation sequencing of the hypervariable regions v3-v4 of the 16S gene. Alpha diversity analyses were performed using the Observed Richness and Shannon diversity index metrics and Beta diversity analyses were conducted using Nonmetric multidimensional scaling with Weighted Unifrac, Differential abundance analysis was performed using a Negative Binomial Wald Test with maximum likelihood estimation for coefficients of Generalized Linear Models.

Results: Newborns of obese mothers exhibited lower alpha diversity compared to newborns of mothers with adequate BMI (body mass index). We observed variation in the composition of the microbial community in newborn stool samples, both from mothers with overweight/obesity and those with adequate pre-pregnancy BMI. We observed a visible correlation between the mode of delivery and the newborn's microbiota. We found variation in the overall composition of the microbial community in the stools of newborns, regardless of the delivery mode.

Conclusions: The results of our study demonstrate differences in the microbiota of neonates born via cesarean section compared to those born vaginally as well as differences in newborns of mothers with overweight/obesity compared to those with an adequate pre-pregnancy BMI.