Cesarean-delivered infants show reduced Bacteroides and Bifidobacterium, and increased Enterococcus and Veillonella. at 1 year, persistence of this cesarean-associated microbial signature was linked to higher asthma risk by age 6 (HR = 2.11, p = 0.022). Lower microbiota maturity and reduced cytokine responses (e.g., IL-4, IL-13) further suggest impaired immune regulation mediating this association. Here, IL13 is linked to asthma.