Initial meconium microbiome in Chinese neonates delivered naturally or by cesarean section.

Previous studies have revealed significant differences in microbiome compositions between infants delivered via cesarean section (C-section) and natural vaginal birth. However, the importance of the delivery mode in the first days of life remains unclear. Importantly, this stage is minimally affected by infant feeding. Here, we used a metagenomic sequencing technique to characterize the meconium microbiome from the feces of a Chinese cohort of vaginally and C-section-delivered infants, including in vitro fertilization (IVF) newborns, during the first 24 h after birth. Meconium microbiome diversity was higher in vaginally delivered infants than that in C-section-delivered infants. Propionibacterium species were most abundant in the vaginally delivered infants, whereas the C-section group had high levels of Bacillus licheniformis. The two IVF newborns delivered by C-section harbored microbial communities similar to the vaginal microbiome in terms of taxonomic composition. Metabolic functions of the C-section group suffered more from the influence of the dominant group (B. licheniformis), whereas the vaginal group was more homogeneous, with a metabolism dominated by multi-microbes. Moreover, different modes of delivery affected the antibiotic resistance gene (ARG) prevalence. These findings provide novel information for the development of strategies to guide a healthy mode of delivery and promote the formation of healthy microbiota.