Birth by cesarean section may influence risk for childhood asthma

Birth by cesarean section was associated with an increase in risk for childhood asthma, researchers reported in European Respiratory Journal.

“We showed that the metabolic profile in newborns reflecting delivery by cesarean section was associated with an increased risk of childhood asthma in two independent cohorts. The majority of the annotated metabolites, ie tryptophan metabolites and bile acids, have previously been associated with asthma endpoints,” Gözde Gürdeniz, MD, from the Copenhagen Prospective Studies on Asthma in Childhood at Herlev and Gentofte Hospital at the University of Copenhagen, Denmark, and colleagues wrote. “Nonetheless, our study is the first to suggest that pertubations of tryptophan and bile acid metabolism are linked to delivery mode, which may explain the underlying biochemical mechanism whereby cesarean section increases the risk of developing childhood asthma.”

Researchers assessed the influence of birth by cesarean section using liquid chromatography-mass spectrometry metabolomic profiles of dried blood spots from 677 and 387 newborn infants from the Copenhagen Prospective Studies on Asthma in Childhood 2010 and 2000 cohorts. Researchers then evaluated the associations between cesarean section metabolic profile, gut microbiome data and cord blood regulatory T-cell frequency at age 1 week.

In both cohorts, children born by cesarean section had different metabolic profiles compared with children born from a natural delivery (2010 cohort: area under the curve, 0.77; 2000 cohort: AUC, 0.66).

The researchers reported that the metabolic profile of cesarean section was associated with increased risk for asthma in school-age children (2010 cohort: P = .03; 2000 cohort: P = .005).

In addition, cesarean section was associated with a lower abundance of tryptophan, bile acid and phenylalanine metabolites.

Gut bacteria after natural delivery also correlated with cesarean section-discriminative microbial metabolites, which the researchers said suggests that maternal microbial transmission during birth regulates a newborn’s metabolism.

Cesarean section metabolic profile was also associated with cord blood T-cell frequency, according to the results.

“Newborns with a cesarean section metabolic profile had an increased risk of developing asthma in two independent cohorts, suggesting that the inferred risk of asthma from cesarean section is mediated through early-life metabolic pertubations. The underlying metabolites were particularly derivates from the tryptophan metabolism and bile acids, indicative of interactions between the early-life guy microbiome and host immune responses, which adds important knowledge on the effect of cesarean section on risk of asthma and may contribute to development of novel primary prevention strategies,” the researchers wrote.