The Human Milk Microbiome in Mothers of Very-Low-Birth-Weight Infants: A Systematic Review of Recent Clinical Studies

Preterm birth remains a major global health concern, affecting approximately one in ten neonates, with an estimated 15 million infants born prematurely each year. Prematurity and clinical factors such as antibiotics, cesarean delivery, and limited access to mother’s own milk disrupt microbiota development in VLBW infants; although human milk supplies nutrients and a microbial community, its composition and clinical role are not yet well understood. However, the composition and clinical significance of the human milk microbiota (HMM) in VLBW infants remain insufficiently characterized. Background: This review aims to summarize recent evidence (2021–2025) on the microbiome of MOM in mothers of VLBW (<1500 g) preterm infants and to evaluate its potential role in neonatal health. Methods: The study used a systematic literature review, searching PubMed and Google Scholar with predefined criteria and keywords. Results and Conclusions: MOM microbiota of VLBW in infants is dominated by Staphylococcus, Enterococcus, Streptococcus, Enterobacteriaceae, and Acinetobacter, with lower levels of Veillonella, Clostridium sensu stricto, Pseudomonas, Haemophilus, and Bifidobacterium; its diversity increases over lactation, and feeding type influences infant gut colonization and immune development, though links to necrotising enterocolitis (NEC) remain limited. Further research using multi-omic approaches is needed to clarify these mechanisms and their clinical implications.