To promote the health of preterm babies, a better understanding of the interplay between gut microbes, host and diet is needed. For example, specific oligosaccharides from the mother’s milk can module the gut microbiome and significantly reduce the risk of necrotizing enterocolitis and late-onset sepsis in the infant. Based on the multi-omicanalysis of clinical samples, together with microbiome and metabolomic profiling and basic microbiology, we linked diet-microbe-host interactions to a range of health and disease outcomes. We also use a human intestinal organoid model system to advance our gut microbiome work. This session, will cover how the microbiome develops in infants and discuss the potential to develop novel disease biomarkers and targeted therapeutic interventions while focusing on promoting the health of preterm infants.