A new study has bolstered the arguments against choosing to deliver a baby by Caesarian section when it's not medically necessary. According to the research, published in the journal Archives of Disease in Childhood, babies born via C-section are far more likely to be obese as toddlers than babies born vaginally. Here's what you need to know:

How much more likely are C-section babies to become obese?
Twice as likely, according to the study. The researchers tracked 1,250 women who delivered their babies at Children's Hospital of Boston, 284 of whom gave birth by Caesarean section. By the time the kids reached age 3, 15.7 percent of children born by C-section were obese, compared to just 7.5 percent of those delivered vaginally.

What accounts for the difference?
The mothers who delivered by C-section were heavier, on average, than the other moms, and they nursed their babies less. But the risk of obesity among their children was still higher even after controlling for these and other potentially significant factors. The researchers aren't certain what else is at play here, but they speculate that vaginal birth might influence babies' digestion by affecting bacteria in their bellies, or release hormones that could affect metabolism.

But do C-sections actually make kids obese?
Not necessarily. It would take more research to prove that definitively.

Should I avoid C-sections?
That depends. Dr. Amos Grunebaum, an obstetrician in New York City, already tells patients who opt for C-sections strictly out of personal preference that the procedure carries risks — such as the increased likelihood that the newborn will be admitted to intensive care with breathing problems. Now, he says, he'll tell mothers-to-be about the link between C-sections and obesity, too. But Grunebaum also tells WDAM that the risk that a child will wind up overweight is "not a good enough reason" for pregnant women to think twice about a C-section if it's necessary to avoid complications. 

Sources: Blisstree, New York Times, Voice of America, WDAM