Infant Microbiome

The infant gut microbiome plays a critical role in immune, nutritional, and metabolic development. Infant stool tests should not be interpreted using adult reference ranges. Low microbial diversity in the first six months is appropriate for infants rather than deficient. Breastfed infants have higher Bifidobacterium, while formula-fed infants show more opportunistic and pathogenic microbes. Most infant microbiome evidence comes from high-income countries, limiting understanding of low-resource settings. Delivery mode, feeding practices, antibiotic exposure, and household conditions are all expected to influence microbiome trajectories. Colonisation patterns in early infancy clustered on hospital-contact surfaces and maternal personal items, particularly mobile phones. Early-life disruptions to the gut microbiome have been linked to later risks of allergy, obesity, and inflammatory disease. C-section delivery bypasses maternal vaginal and gut microbial seeding and is associated with fewer Bifidobacterium and more opportunistic organisms. Infant microbiome seeding occurs during and after birth through the vaginal canal, swallowed fecal fluid, the environment, and breast milk. The in…