A new study from Harvard T.H. Chan School of Public Health has revealed that children born by cesarean delivery were 15 percent more likely to become obese than those born by vaginal birth. The study, which was published Tuesday in JAMA Pediatrics, also added that the risk of obesity may persist through adulthood.

The obesity problem is 64 percent more likely to be present in individuals born via cesarean delivery than their siblings born by vaginal birth, the study added. Researchers have found that individuals born via vaginal birth among women who had undergone a previous cesarean delivery were 31 percent less likely to become obese compared with those born via cesarean birth following a cesarean birth.

"Cesarean deliveries are without a doubt a necessary and lifesaving procedure in many cases," Jorge Chavarro, associate professor of nutrition and epidemiology at Harvard Chan School and senior author of the study, said. "But cesareans also have some known risks to the mother and the newborn. Our findings show that risk of obesity in the offspring could another factor to consider."

In the United States, nearly 1.3 million cesareans are performed each year -- a number that is one third of all deliveries. While a number of previous studies have suggested a link between cesarean delivery and a higher risk of obesity in offspring, the studies were either too small to detect a clear association or lacked detailed data.

The current study was performed after an analysis of 16 years' worth of data from 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 study was conducted by researchers looking at the participants' body mass index (BMI) over time. They also looked into other factors such as whether they were delivered via cesarean section. The mothers' pre-pregnancy BMI, smoking status, age at delivery, and where they lived, were also factors that were taken into consideration during the analysis.

"I think that our findings--particularly those that show a dramatic difference in obesity risk between those born via cesarean and their siblings born through vaginal delivery--provide very compelling evidence that the association between cesarean birth and childhood obesity is real," Chavarro said. "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."

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