Kids Born Via C-Section Are More Likely To Be Obese, Study Finds

And no, it has nothing to do with their mothers' weight.

A new study is shedding more light on the curious connection between caesarean sections and obesity in kids and young adults.

Simply being delivered via C-section leaves kids with an average 15 percent higher chance of being obese than those born through the birth canal, according to a study published in the journal JAMA Pediatrics.

Though additional research is needed to confirm how and why this happens, it may be because C-section babies are deprived of the transfer of healthy bacteria from the birth canal that could play a role in weight regulation.

“At birth, our bodies are colonized by bacteria,” study co-author Audrey Gaskins told ResearchGate. “Children born by vaginal delivery are primarily exposed to their mothers’ vaginal and gut microbes, whereas children born by cesarean are primarily exposed to bacteria on their mothers’ skin and whatever bacteria happen to be in the air in the operating room.”

For the new study, a team led by researchers at Harvard’s T.H. Chan School of Public Health analyzed data on 22,068 young adults who are part of the long-term Growing Up Today study. Participants in the study regularly respond to questionnaires starting after the age of nine until they are in their late 20s; their mothers are enrolled in a second ongoing study so data can be linked.

Researchers found that among this large group, C-section births resulted in a 15 percent greater risk of obesity for both boys and girls. Researchers found similar obesity rates at all three ages they measured the subjects: As pre-adolescents (ages 9-12), adolescents (ages 13-18) and young adults (ages 19-28).

It has nothing to do with a mother’s weight.

Women who are obese are more likely to have C-sections, but not as much is known about the effect of C-sections themselves, Dr. Jorge Chavarro, one of the study’s coauthors, told HuffPost. In fact, this was one of the main motivations for the report.

“Several studies had previously reported that children born by cesarean were more likely to become obese later in life, but most of these studies did not have information on maternal weight status before pregnancy,” Chavarro said.

His team found the higher risk for obesity among C-section children held true even after controlling for factors including pre-pregnancy body mass index and other potential contributors to obesity risk such as mother’s age at delivery, race and region of birth.

More study is needed to pinpoint exactly why C-sections influence weight gain, the report says, but experts suspect it could be due to that missing bacteria: When most babies pass through the birth canal, they pick up a variety of bacteria that help them digest milk and break down food. C-section babies, however, don’t get exposure to such a vast array of microbes, and may more readily become obese as a result.

The authors note that C-sections are necessary and life-saving in many cases, but suggest future moms with options should consider consider the findings when determining a birth plan.

Facts About Childhood Obesity