A new paper in the British Medical Journal by Jan Blustein, MD, PhD, of New York University's Wagner School and a professor of Medicine and Population Health at NYU School of Medicine and Jianmeng Liu of Peking University examines the evidence as to whether newborns delivered by C-section are more likely to develop chronic diseases later in life. While the jury is still out and research is ongoing, recent studies underscore the need for health care providers to discuss with expectant parents the risk of babies born through cesarean section developing obesity, asthma, and diabetes, according to the paper by Blustein and Liu.

Cesarean section is sometimes a medical necessity, or even an emergency. But it is increasingly a choice made in cooler moments. C-section on mothers' request is growing globally. At the same time, while repeat cesarean is not necessarily medically indicated for women with otherwise low obstetrical risk, there is a 90% repeat cesarean rate among women giving birth who have had a prior cesarean, in the US.

While cesarean and vaginal deliveries are both associated with well-known acute risks, recent studies link C-section to long-term child chronic disease. The authors review this evidence from a variety of sources. These include observational studies where researchers locate large samples of children, assess the extent of disease, and look back to see how the children were delivered. They also include a clinical trial, in which mothers were prospectively randomized to undergo cesarean or vaginal delivery. The authors find that the evidence warrants concerns that C-section may lead to worse long-term child health.

These risks have yet to be mentioned in clinical guidelines, which are the official documents that are used to educate doctors and midwives. "It's time to update the guidelines to include information about possible risks to long-term child health," comments Dr. Blustein.

She acknowledges that the evidence linking cesarean to worse child health is not unequivocal. "It is clear that cesarean-born children have worse health, but further research is needed to establish whether it is the cesarean that causes disease, or whether other factors are at play," Dr. Blustein says. "Getting definitive answers will take many years of further research. In the interim, we must make decisions based on the evidence that we have. To me, that evidence says that it is reasonable to believe that cesarean has the potential for long-term adverse health consequences for children."

"It takes awhile for research findings to reach clinicians and patients," says Blustein. "This research isn't widely known. It is time for that to change, so that doctors, midwives and patients can weigh the risks and benefits of elective cesarean, and decide accordingly."