A new study has found that babies who are delivered through Caesarean section are twice as likely to become obese than those born traditionally.

Researchers from Boston Children’s Hospital in Massachusetts have published a study which suggests a doubling in the odds of obesity by the time the child was three years old. This has been linked to bacteria in the gut which is caused by the C-section. This could then affect the way food is digested, leading to the offspring becoming overweight.

The study is based on results collected from 1,255 pairs of mothers and children from 1999 to 2002, and has been published in the Archives of Disease in Childhood. Of the mothers surveyed, around one in four were C-section births and the remainder were vaginal deliveries.

After the results were collected, the research team found that there was a link between body mass, skin thickness and how a child was born. Additionally, they found that mothers who chose to deliver by C-section tended to be more overweight than those who delivered traditionally, and this could have affected the weight of the child.

But the researchers hypothesised another explanation, which was that a difference in the composition of gut bacteria acquired at birth could be a causal factor of obesity. They found significant differences in the gut bacteria between C-section and traditional methods.

If these results are found to be correct, the researchers have proposed that expectant mothers should be advised on the potential side effects of a caesarean before undergoing with the procedure. At the moment, only 23 per cent of births in the UK are delivered by C-section.

Patrick O’Brien, a spokesman for the Royal College of Obstetricians and Gynaecologists, said: “This is an interesting study, but small. It needs to be replicated in a bigger sample.”