Study Finds Link Between C-section and Obesity

In a new mice study, it has been found that being born by Caesarian section, or C-section, may increase the risk of obesity, and cause changes in gut microbiome.

Caesarean section, also known as caesarean delivery, is the surgical procedure wherein a surgical incision is made in the mother’s abdomen and uterus to deliver one or more babies.

The latest animal study led by researchers from NYU School of Medicine suggests the mode of delivery interferes with the mice’s gut microbiome- the set of microorganisms that live in the digestive tracts of humans and animals, increasing their likelihood of becoming obese or overweight.

“C-section leads to increased body weight gain in a mammal model. In humans, there is epidemiological evidence that this happens too,” said study coauthor Maria Gloria Dominguez-Bello of New York University School of Medicine.

For the study, Dominguez-Bello and colleagues looked at the weight of 34 mice delivered by C-section and compared them with 35 mice born vaginally, and tracked them for 15 weeks.

They found, Caesarian section mice had put on 33 percent more weight in the 15 weeks after weaning than the mice delivered vaginally.

Further investigation showed that female mice born via C-section gained 70 percent more weight compared with their vaginally delivered peers. On the other hand, C-section male mice gained only 14 percent more weight than those born naturally.

“Our study is the first to demonstrate a causal relationship between C-section and increased body weight in mammals,” said Dominguez-Bello.

Along with weight gain, the researchers witnessed significant changes in the development of the microbiome in the mice’s gut. They found, the bacterial species in the guts of mice born by C section did not change structurally or mature to match microbiome of older mice in the six weeks. But both the structural changes and maturation were seen in the gut bacteria of mice born vaginally.

Dominguez-Bello and colleagues hypothesise that microbiota transmitted from mothers to vaginally delivered pups protected them against weight gain. They found three bacterial groups – Bacteroides, Ruminococaceae, and Clostridiales- in abundance in pups delivered vaginally. In the past, these bacteria groups had been linked to leaner body type in mice, the researchers said.

“Further research is needed to determine whether the dominance of certain bacterial groups can protect against obesity,” Dominguez-Bello said. “Our results support the hypothesis that acquiring maternal vaginal microbes is needed for normal immune and metabolic development.”

The result were published online on Wednesday (October 11) in Science Advances.