"Although caesarean section deliveries are a necessary lifesaving procedure in many cases, they also include known risks to mothers and newborns," said Jorge Chavarro, Associate Professor at Harvard T.H. Chan School of Public Health School.
"The study provides very compelling evidence that the association between caesarean birth and childhood obesity, is real," Chavarro added.
The findings showed that within families, children born by caesarean section were 64 per cent more likely to be obese than their siblings born by vaginal delivery.
Explaining this, Chavarro stated: "That's because, in the case of siblings, many of the factors that could potentially be playing a role in obesity risk, including genetics, would be largely the same for each sibling, except for the type of delivery."
Further, individuals born via vaginal birth among women who had undergone a previous C-section delivery were 31 per cent less likely to become obese compared with those born via C-section.
For the study, the team analysed more than 22,000 young adults in the Growing Up Today Study (GUTS), in which participants answered survey questions every year or two years from 1996-2012.
The researchers looked at the participants' body mass index (BMI) over time at whether or not they were delivered via caesarean and at other factors that could play a role in obesity, such as the mothers' pre-pregnancy BMI, smoking status, age at delivery, and where they lived.
They also looked at whether the mothers had previous caesarean section deliveries.
The results were published online in the journal JAMA Pediatrics.
