Dynamics and drivers of the human breast milk microbiome across lactation stages.

Introduction: Human breast milk (HBM) not only provides all the nutrients and microbiota for the initial development of infants but is also the source of gut microbes in infants and is essential for establishing a healthy gut microbiota and immune system. In this study, we enrolled 188 healthy Uyghur mothers from Xinjiang, China, analysed the structure and diversity of the human breast milk microbial community from 0 to 856 days after delivery, and explored the characteristics of the human breast milk microbiome and potential influencing factors at each lactation stage. Methods: By constructing microbial cooccurrence relationship networks at various stages of lactation and random forest models, we adopted large sample collection and combined multiple models to largely avoid individual differences. Results: We showed that the human breast milk microbiota is a dynamic and complex ecosystem, and we found the network central nodes that change during the transition from human colostrum to human mature milk and various stage specific microbial markers. In addition, we also found that the mode of delivery and intrapartum antibiotic prophylaxis during delivery affected the structure and diversity of the microbial community of colostrum, but the degree of influence decreased as the human colostrum transitioned to mature milk. Discussion: We determined the change trends for microbial community structure and diversity during the transition from human colostrum to human mature milk, provided evidence for the temporal dynamics of the microbial community in human breast milk, and evaluated the impact of potential factors, such as mode of delivery on the microbes in human breast milk. These findings have potential implications for the health and development of infants.