Asthma risk with cesarean section deliveries may be caused by microbiome differences

An elevated risk for developing asthma among children delivered by cesarean section may be caused by differences in their gut microbiome, according to research published in Science Translational Medicine.

“Every generation of mothers hands over its microbiome to the next, as the baby is coated with beneficial germs while being squeezed through the birth canal — but this doesn’t happen for babies born through C-section,” Martin Blaser, MD, director of the Center for Advanced Biotechnology and Medicine at Rutgers University, said in a press release. “It takes a while for babies born through C-section to develop a normal microbiome. And during that time, while the immune system is also developing, they become more at risk for later-developing certain diseases like asthma.”

Blaser and colleagues evaluated children from the Copenhagen Prospective Studies on Asthma in Childhood 2010 mother-child cohort who were followed prospectively from birth. They assessed fecal samples from children obtained at 1 week, 1 month and 1 year after birth, and characterized them using 16S ribosomal RNA gene amplicon sequencing.

Among the 700 children assessed in the study, 22% were delivered via cesarean section and 78% were delivered vaginally.

Blaser and colleagues found significant differences in the composition of children’s gut microbiota based on whether they were delivered vaginally or by cesarean section.

Among the 653 children with information available for the full follow-up period, the prevalence of asthma was 7%, and 15% of children were in remission from an asthma diagnosis.

The researchers determined that the risk for asthma by the age of 6 years was greater in those born via cesarean section (OR = 2.45; 1.32-4.55, P = 0.004), with 13% of those delivered via C-section and 6% of those delivered vaginally developing asthma by the age of 6 years.

Blaser and colleagues found that children born by cesarean section who had a low cesarean section microbial score at 1 year had a similar risk for developing asthma as those who were born vaginally. However, children who still had a high cesarean section gut microbial score at 1 year had a risk for developing asthma more than 3 times greater than those with a low cesarean section microbial score (OR = 3.56; 1.09-11.65, P = 0.035).

The researchers said this finding suggests that achieving an appropriately matured gut microbiota could lower the risk for asthma associated with changes to the gut microbiome in those delivered by cesarean section.

“Even though a child is born by caesarean section and has an immense early microbial perturbation, this may not lead to a higher risk of asthma if the microbiome matures sufficiently before age 1 year,” Jakob Stokholm, MD, PhD, a senior scientist at the Copenhagen Prospective Study on Asthma in Childhood and first author of the study, said in the press release. “Our study proposes the perspective of restoring a caesarean section–perturbed microbiome and thereby perhaps prevent asthma development in a child, who is otherwise at high risk.”

References:

Stolkholm J, et al. Sci Transl Med. 2020;doi: 10.1126/scitranslmed.aax9929.

Press Release.