Mother-to-offspring microbial vertical transmission: timing, determinants, and impact on offspring susceptibility to gastrointestinal diseases.

The establishment of the early-life microbiota is profoundly shaped by microbial vertical transmission from mother to offspring. This review synthesized the current understanding of the timing, determinants, and health implications of mother-to-offspring microbial vertical transmission. We detailed the contentious evidence regarding prenatal microbial transmission and highlighted the well-established roles of intrapartum and postnatal transmission via birth and breastfeeding, respectively. Multiple factors, including delivery mode, gestational age, feeding patterns and antibiotic exposure, are critical modulators of microbial transmission, shaping the initial microbial community. Emerging intervention strategies, such as breastfeeding, probiotic supplementation, vaginal microbiota transplantation, and fecal microbiota transplantation, offer promising avenues for restoring a healthy microbial trajectory when natural transmission is disrupted. This review underscores that vertical transmission is the cornerstone of intergenerational microbiome inheritance and a potential therapeutic target for preventing early-life dysbiosis and associated diseases.