A large new study by Harvard Public Health researchers discovered individuals born by cesarean delivery were 15 percent more likely to become obese as children than individuals born by vaginal birth.
Investigators found the increased risk may persist through adulthood, and individuals born via cesarean delivery were 64 percent more likely to be obese than their siblings born by vaginal birth.
The study appears online in JAMA Pediatrics.
Researchers also discovered 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.
Experts believe the association between cesarean deliveries and obesity should be transparent to all stakeholders.
“Cesarean deliveries are without a doubt a necessary and lifesaving procedure in many cases,” said Dr. Jorge Chavarro, associate professor of nutrition and epidemiology at Harvard Chan School and senior author of the study.
“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.”
Nearly 1.3 million cesareans are performed each year in the U.S., accounting for 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 new study sough to rectify the data shortage as researchers analyzed 16 years’ worth of data from more than 22,000 young adults in the Growing Up Today Study (GUTS). This data set stemmed from a survey in which participants answered 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 cesarean (using information collected from participants’ mothers, participants in the Nurses’ Health Study II); and at other factors that could play a role in obesity.
The additional factors included a mothers’ pre-pregnancy BMI, smoking status, age at delivery, and where they lived. Researchers also looked at whether the mothers had previous cesarean deliveries.
“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,” said Chavarro.
“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.”