The hidden reason why children born by cesarean section are more likely to develop asthma

Researchers at Rutgers University, Copenhagen Prospective Studies on Asthma in Children and the University of Copenhagen have described for the first time how cesarean delivery interferes with a baby’s ability to obtain beneficial germs in the mother’s microbiome, and how this can lead to childhood asthma.

The study, published in Scientific translational medicine, has implications for understanding the role of cesarean delivery in potentially skewing a child’s microbiota – the trillions of beneficial microorganisms that live in and on our bodies – and how this can influence health. This could lead to new prevention strategies, including targeted efforts to correct disturbances in a child’s microbiome.

“Each generation of mothers passes their microbiome on to the next, as the baby is covered in beneficial germs while being pressed into the birth canal – but this does not happen for babies born by cesarean section,” said co-author Martin Blaser, director of the Center for Advanced Biotechnology and Medicine at Rutgers. “Babies born by cesarean section take a while to develop a normal microbiome. And during this time, as the immune system is also building, they become more at risk of later developing certain diseases like asthma. This study provides a mechanism for the known link between cesarean birth and increased risk of asthma. “

Researchers analyzed the effects of vaginal birth versus cesarean section in the first year of life for 700 children. To determine if the type of birth was causing microbiome disturbances and if these were associated with asthma, they examined fecal samples from children at one week, month, and year to determine microbial diversity and maturity. .

Researchers found that cesarean delivery was associated with a more than doubled risk of asthma and subsequent allergies, as well as significant changes in the composition of the gut microbiota. However, at one year, the risk of asthma was reduced in children born by Caesarean section if their gut microbiota had recovered from its initial disturbance and began to mature normally.

“Even if a child is born by Caesarean section and has immense early microbial disruption, it may not lead to a higher risk of asthma if the microbiome matures sufficiently before the age of 1,” says Jakob Stokholm, senior scientist to The Copenhagen Prospective Study on Childhood Asthma and the study’s first author. “Our study offers the prospect of restoring a microbiome disrupted by a cesarean section and thus possibly preventing the development of asthma in a child, who is otherwise at high risk.”