There may be a link between manner of birth and obesity, suggests a new study.

Delivery by Caesarian section is the accepted alternative mode of birthing when natural (vaginal) delivery causes a problem for mother and baby. But a new study revealed that C-section may also have side effects once the baby reaches adulthood.

Imperial College London researchers found out that C-section babies are more likely to develop weight problems in their adulthood compared to babies delivered the natural way. The team studied 15 cases from 10 countries involving 38,000 people to reach their conclusion.

The result of their investigation showed that those born through C-section were 26% more likely to be overweight or obese once they reach adulthood. They also found out that adults born through C-section had a higher body mass index (BMI) than those born through vaginal delivery.

Dr Matthew Hyde, one of the researchers, explained that there is a difference in the frequency of certain healthy bacteria in the gut of C-section babies and babies delivered naturally. These bacteria may have a direct link on genes and the metabolism of the baby, which in turn influence body weight.

While researchers said their work is the largest so far to show a link between manner of delivery and obesity, they admitted that they still need to consider other factors that may play a role in the link. Professor Neena Modi, the senior author, said they are now considering biological mechanisms to explain the link between C-section delivery and obesity.