# A Metagenomic Comparison of the Colostrum Microbiome in Bulgarian Mothers by Delivery Mode: A Pilot Study

## TL;DR

This study compares the colostrum microbiome in Bulgarian mothers based on delivery mode and finds subtle differences in bacterial composition.

## Contribution

The study provides new insights into how delivery mode influences the colostrum microbiome in a Bulgarian population.

## Key findings

- No significant differences in overall microbial diversity between vaginal and cesarean delivery groups.
- Distinct bacterial taxa and functional profiles were associated with each delivery mode.
- Inter-individual variability was a prominent feature of the colostrum microbiome.

## Abstract

Colostrum harbors a highly diverse microbial community, predominantly composed of genera such as Staphylococcus, Streptococcus, Lactobacillus, Bifidobacterium, and Enterococcus. The composition and diversity of this microbiota are influenced by maternal factors—including age, body mass index, lactation activity, stress levels, and gestational diabetes—as well as external factors such as mode of delivery, antibiotic exposure, diet, and geographic location. This microbial community plays a critical role in maternal and neonatal health by contributing to early gut colonization, supporting digestion, promoting immune system development, and protecting against pathogenic microorganisms through mechanisms such as antimicrobial peptide production by lactic acid bacteria. The primary aim of this study was to evaluate the impact of mode of delivery on colostrum microbiota by comparing mothers who delivered vaginally with those who underwent cesarean section. Colostrum samples from 15 mothers were subjected to DNA extraction, high-throughput sequencing, and bioinformatic analyses to characterize microbial composition and predicted functional profiles. Although substantial inter-individual variability was observed, no statistically significant differences were detected in overall microbial diversity or community structure between the two delivery groups. However, distinct bacterial taxa and functional characteristics were identified that were specific to each mode of delivery, suggesting subtle delivery-related influences on colostrum microbiota composition.