Babies delivered by caesarean section tend to have altered gut microbiota and are more prone to colonization by bacteria that potentially cause disease, according to a report in Nature. In the largest known study of its kind, the results confirm previous findings suggesting that the mode of delivery is a major factor that shapes the gut microbiota in the first few weeks of life.
Newborn babies acquire microorganisms from their mothers and surrounding environment that seed their gut microbiota; disruption of this process has been associated with the development of some diseases in childhood or later in life. Previous attempts to understand what influences the composition of the gut microbiota in babies during the first month of life (the neonatal period) have been limited by small sample sizes and poor resolution of the microbiota.
Trevor Lawley and colleagues performed whole-genome sequencing of the human gut microbiota in 596 full-term babies born in UK hospitals to determine how birth by caesarean section shapes the composition of the microbiota during the neonatal period. Of the babies studied, there were 314 vaginal births and 282 were delivered via caesarean section. The analyses revealed that delivery by caesarean section was associated with disrupted transmission of maternal commensal bacteria and a higher incidence of colonization with drug-resistant opportunistic pathogens, which are likely to be of environmental origin. Around 83% of babies delivered by caesarean section were found to carry potentially pathogenic bacteria, compared with around 49% of the vaginally delivered babies. Maternal antibiotic use accounted for the greatest amount of variation in the composition of gut microbiota in vaginally delivered babies.
The clinical consequences of disruptions to gut microbiota and presence of pathogens in early life remain to be determined, the authors conclude.