To evaluate how the mode of birth and perinatal antibiotic exposure, independently and together, influence infant gut-microbiota composition, diversity and early health outcomes.
Approach:
Design: Systematic review and meta-analysis conducted in accordance with PRISMA 2020 and registered with PROSPERO.
Data Sources: MEDLINE, Embase, Web of Science and Cochrane CENTRAL from inception to October 2024.
Eligibility Criteria: Randomised controlled trials, cohort or case–control studies of healthy term infants comparing vaginal versus caesarean birth and/or perinatal antibiotic exposure.
Key Findings:
No statistically significant difference in bacterial abundance between vaginally delivered and caesarean-born infants (mean difference 3.44%, 95% CI −2.00 to 8.89; I² = 99%; very low certainty).
Among antibiotic-exposed infants, the mean difference in bacterial abundance was -0.31% (95% CI −3.52 to 2.89).
Exploratory trend towards higher bacterial abundance following vaginal delivery among antibiotic-unexposed infants.
Consistent reductions in microbial diversity and depletion of Bacteroides and Bifidobacterium following caesarean birth or perinatal antibiotic exposure.
Exclusive breastfeeding associated with partial restoration of microbial balance.
Interpretation:
Caesarean delivery and perinatal antibiotic exposure are associated with differences in gut microbiota composition and diversity, with exclusive breastfeeding mitigating some negative effects.
Limitations:
Imprecision in estimates and inherent limitations of observational data, including potential confounding factors.
Conclusion:
Further research is essential to explore the long-term health implications of altered gut microbiota.
