Improving immune-related health outcomes post-cesarean birth with a gut microbiome-based program: A randomized controlled trial.

Background: Infants born via Cesarean section (C-section) often have a distinct gut microbiome and higher risks of atopic and immune-related conditions than vaginally delivered infants. We evaluated whether a microbiome-based program could shift gut microbiome composition and improve microbiome-associated health outcomes in C-section born infants.

Methods: This open-label, randomized, controlled trial included full-term C-section-born infants aged 0-3 months, randomized to an intervention (n = 25) or control arm (n = 29). Over 6 months, the intervention arm received two microbiome reports, personalized recommendations based on their microbiome, educational materials, and coaching calls focused on microbiome health. Parents reported health conditions via surveys.

Primary Outcome: Difference between study arms in relative abundance of key gut microbiome taxa and functional genes. Other outcomes: Changes in a C-section index-a taxonomy-based metric comparing C-section-associated taxa to vaginally-associated taxa-and prevalence of atopic conditions.

Results: Compared to controls, the intervention arm had higher Bifidobacterium (p = .025, q = .121) and higher abundance of genes associated with human milk oligosaccharide degradation (e.g., α-L-fucosidase, p = .019, q = .046) at timepoint 2. In the intervention arm, the C-section index decreased to a level similar to vaginally born infants (p = .807, q = .807). At the end of the intervention, atopic dermatitis prevalence was lower in the intervention arm than in controls (odds ratio, 0.17 [95% CI, 0.023-0.723], p = .031).

Conclusion: A personalized microbiome-based program can modulate the gut microbiome of C-section-born infants and may reduce the risk of atopic conditions (ClinicalTrials.gov: NCT06424691).