Cesarean babies have lower levels of ‘good’ gut bacteria, a new study shows. This may make them more prone to respiratory infections, but the overall health effects are unclear.

Over the past few years, gut bacteria have been increasingly shown to play an important role in our overall health. The bacteria in the gastrointestinal tract can help regulate the immune system, and recent studies have shown that altering these microbial communities can cause autoimmune disorders and many other problems.

With this in mind, a team of researchers set out to see whether natural birth and C-section would have an impact on babies’ microbiome. They analyzed over 100 babies (46 babies born by cesarean section and 74 babies born vaginally), finding that those who were born vaginally had a significantly different gut microbiome make-up. Although the differences were found to diminish over time, they were significant enough to potentially make cesarean babies more prone to infections. Furthermore, babies born through C-sections were also slower to acquire “good bacteria” that can help them to digest milk.

Researchers aren’t sure why these differences appeared, but there was a suspicion that it could be because many mothers who’ve had cesarean sections required antibiotics. But the antibiotics were only given to the mother after the baby had been delivered — meaning the baby wasn’t directly exposed to antibiotics.

“We feel that it is proved that mode of delivery is an important driver or modifier of the gut microbiome in young infants,” Prof Debby Bogaert from the University of Edinburgh, who worked on the project with colleagues in the Netherlands, told The Guardian.

The researchers also found that antibiotics given to mothers after birth did not appear to affect the mothers’ microbiome. Furthermore, the differences in babies’ microbiomes were also seen in babies that were only bottle-fed — suggesting that there are more factors at play than just the type of birth.

It’s hard to draw a cause-effect relationship. The study only found a correlation and it’s still a relatively small sample size. However, one thing is becoming increasingly clear: we need to pay more attention to the gut microbiome of both babies and adults. Key bacterial components could be administered artificially to C-section babies, for instance, or their health could be monitored more closely for types of infections linked with gut microbiome unbalances.

Hopefully, more studies can clarify exactly what effect the method of delivery has on babies’ microbiome, and how this difference translates into health outcomes.

“The concept of foetal microbiome is very controversial,” concludes Katja Korpela, one of the researchers involved in the study from the University of Oulu, Finland.

The research was presented at the European Congress of Clinical Microbiology and Infectious Diseases in Amsterdam, Netherlands.