Gastrointestinal consequences of cesarean section birth: A systematic review of short- and long-term effects in infancy and beyond

Table 8 Summary of gut microbiota differences by delivery mode

Feature	Vaginal delivery	C-section
Initial colonizers	Lactobacillus, Bifidobacterium, Bacteroides	Enterococcus, Staphylococcus, Klebsiella
Microbial diversity	High	Reduced
Commensal dominance	Yes	Delayed or absent
Opportunistic pathogen presence	Low	High (esp. hospital-acquired)
Persistence of differences	Normalize by 6-12 months	May persist > 12 months
Transmission from mother	Effective vertical transmission	Severely reduced; environmental transmission
Modifiable by breastfeeding	Enhanced commensal colonization	Partially restores microbial balance
Effect of Intrapartum Antibiotics	Reduces vertical transmission in VD	Present in all C-section deliveries
Racial/geographic variation	Present (e.g., Japanese, Korean, United Kingdom cohorts)	Yes, with consistent patterns across populations
Corrective interventions	Less needed	FMT, probiotics, breastfeeding are critical

C-section: Cesarean section; FMT: Fecal microbiota transplant; VD: Vaginal delivery.