New evidence supports link between C-sections and obesity

Researchers suspect lack of exposure to vaginal microbes is to blame.

In a new study, researchers compared the weight gain and gut microbes of mice born by C-section to those born vaginally. Those born by C-section gained on average 33 percent more weight in the 15 weeks after weaning. Currently, C-section births are common in many parts of the world, making up 33 percent of births in the US, and around 50 percent in Brazil, the Dominican Republic, Italy, and Iran. We spoke with the study’s lead author, microbiologist Maria Dominguez-Bello, to learn more about her findings and their implications.

ResearchGate: What motivated you to conduct this study? 

Maria Dominguez-Bello: There is evidence that C-section born infants have increased risk of obesity, type 1 diabetes, celiac diseases, allergies, and asthma, what we call the modern plagues. These are diseases increasing with urbanization.

RG: What did you find? 

Dominguez-Bello: We found that in mice, C-section-fostering caused increased weight gain, and an abnormal microbiota that seems to not mature much during the baby’s development.

RG: Why do you think mice born by Caesarian gained more weight? 

Dominguez-Bello: We think it’s microbes, but we need to prove it. We still have not shown causation by the microbes alone.

RG: What differences in the microbiomes of mice born by C-section and those born vaginally did you see? 

Dominguez-Bello: We found that vaginally born mice have increased Bacteroides, Ruminococcaceae, and Clostridiales compared to mice delivered by C-section. These three bacterial groups have been previously associated with a lean body phenotype in mice.

RG: How likely is it these findings translate to humans? 

Dominguez-Bello: Humans are not mice, but they are mammals, and we share a lot of our biology with mice. If something promotes growth or inflammation in mice, it is likely to work in humans. Although of course our microbes are the human versions.

RG: Would it be possible to expose mice or children born by C-section to the microbes they’d encounter in a vaginal birth?

Dominguez-Bello: A previous study from our lab showed that, in humans, babies born by Cesarean could have their microbiota restored, meaning their bacterial communities looked more similar to those in babies born vaginally.  However, we still do not know if microbiota restoration reduces the disease risks associated with Cesarean birth.

RG: Do you recommend women avoid C-section births? 

C-sections, like antibiotics, are life-saving intervention when needed. I recommend not to opt for a C-section when not medically necessary. We need to invest in research to optimize labor, respecting its natural course, but using our technology and techniques to optimize it.

Only until very recently they had women going through labor lying on their backs, immobilized and alone. This often the way it’s done in developing countries. No wonder women choose to have C-sections. I think we have the knowledge and the technology to improve natural birth, but more funding and research are needed to change medical practice.

Featured image courtesy of Allen Foster