CAESAREAN section (CS) birth has previously been linked to early disruption of the infant gut microbiome, but new research suggests that exposure to specific bacteria and older siblings may help restore microbial balance within the first year of life.
The infant gut microbiome is essential for immune development, and disruption following CS has previously been associated with an increased risk of childhood asthma.
Whether this altered microbial profile can recover, and what factors may influence this process, has remained unclear.
Infant Gut Microbiome Restoration After Caesarean Section
In this study of 700 children from a prospective birth cohort, researchers developed a “restoration score” to assess how closely the gut microbiome at 1 year resembled that of vaginally delivered infants. This infant gut microbiome restoration score enabled the team to quantify recovery and investigate early-life predictors.
The findings showed that gut microbiome composition at 1 week of age was a predictor of the restoration score at 1 year. This suggests that early microbial patterns may play an important role in shaping later microbiome development.
Notably, infants with older siblings had significantly higher restoration scores. This association appeared to be driven by increased exposure to beneficial bacteria, likely transferred through close household contact.
The findings were replicated in an independent Canadian cohort, supporting their robustness across populations.
Early-Life Bacteria, Microbiome Restoration, and Asthma
Importantly, the findings suggested that microbiome disruption associated with CS delivery may be modifiable rather than permanent. Early bacterial exposures, particularly in the first weeks of life, appeared to influence whether the microbiome developed towards a more typical profile by 1 year.
However, as an observational study, causal relationships could not be confirmed. While the restoration score incorporated asthma outcomes into its broader analysis, further research is needed to determine whether improving microbiome restoration directly reduces asthma risk.
Overall, the findings suggested that the infant gut microbiome is dynamic and responsive to early-life environmental influences, with sibling exposure emerging as a potentially important factor in shaping microbial development after CS delivery.
Reference
Jiang J et al. Early life bacteria and sibling exposure associate with restoration of the infant gut microbiome after cesarean section. Nat Commun. 2026;DOI:10.1038/s41467-026-71185-6.
Featured image: Tomsickova on Adobe Stock
