A new systematic review has found that both the way a baby is born and exposure to antibiotics around the time of birth could be linked to differences in the development of the infant gut microbiome. The review also found that exclusively breastfeeding babies born by caesarean section or exposed to antibiotics may reduce these differences.
However, the authors emphasise that the long-term health implications of these differences remain unclear.
The study, published in BMJ Paediatrics, was led by Bournemouth University, in partnership with University Hospitals Dorset and analysed data from more than 5,300 healthy infants across eleven previousstudies. This systematic review is the first to examine the combined influence of type of birth and perinatal antibiotic exposure on the developing gut microbiome.
The gut microbiome - the community of bacteria and other microorganisms living in the digestive tract - plays an important role in developing the immune systems and overall metabolic health during early life.
The research team found consistent evidence that babies born by caesarean section or exposed to antibiotics around the time of birth tended to have differences in the composition of their gut bacteria, with less diversity, compared with babies born vaginally without antibiotic exposure. Beneficial bacterial groups such as Bacteroides and Bifidobacterium were often less abundant.
However, the authors caution that the differences were not significant and the overall certainty of the evidence was rated as very low because most of the included studies were observational and produced variable results.
The study also found that breastfeeding could mitigate some of the deficiencies in gut bacteria development. Across several studies, exclusively breastfed infants appeared to show a partial restoration of microbial balance, suggesting breastfeeding may help support healthy microbiome development even when babies are born by caesarean section or exposed to antibiotics.
Two mothers with lived experience contributed to the review and welcomed the findings on breastfeeding. They highlighted that many parents face barriers to breastfeeding and called for greater support from healthcare services, employers and wider society to help families who wish to breastfeed do so successfully.
The researchers stress that the findings should not discourage caesarean births or antibiotic use, as these are often essential parts of maternity and neonatal care, helping to protect the lives and health of mothers and babies. The study does not suggest that these interventions should be avoided when medically needed.
"This review is the first to examine birth method and antibiotic exposure together, giving us a more complete picture of how these common early-life experiences may influence the infant gut microbiome. Although we found some consistent patterns, the long-term implications for children's health remain unclear," said Dr Heidi Singleton, Senior Lecturer in Children and Young People's Nursing at Bournemouth University.
"The most encouraging finding was the potential role of breastfeeding. Across several studies, babies who were exclusively breastfed appeared to show recovery of beneficial gut bacteria following caesarean birth or antibiotic exposure. While more research is needed, these findings highlight the importance of ensuring families have access to evidence-based feeding information and support. We hope this research helps drive greater understanding of the benefits of breastfeeding and encourages a culture where families who choose to breastfeed are empowered at home, in the workplace and throughout their communities," she added.
Professor Minesh Khashu, Consultant Neonatologist and Professor of Perinatal Health at University Hospitals Dorset, who was senior author on the study, said "These findings warrant further exploration of this through appropriately designed and funded studies and we plan to set up a cohort in Dorset to investigate this further. It is also important to provide adequate support for breastfeeding within health care systems and society at large."
