Vaginal and Endometrial Microbiome: The Next Frontier in Infertility and Gynecological Disorders

The female reproductive tract microbiome particularly Lactobacillus-dominant (LD) vaginal communities has emerged as a key determinant of reproductive outcomes. Evidence links vaginal dysbiosis and non-Lactobacillus–dominant endometrial communities with infertility, Recurrent Implantation Failure (RIF), and adverse In-vitro Fertilization (IVF) outcomes, while highlighting substantial methodological pitfalls in low-biomass endometrial sampling. This narrative, evidence-based review synthesizes contemporary data on (1) physiology and measurement of the vaginal/endometrial microbiome, (2) associations with infertility, RIF, recurrent pregnancy loss (RPL), endometriosis, and gynecologic pathology, (3) interventional options (antibiotics, probiotics, vaginal microbiota transplantation), and (4) a pragmatic clinical framework for ART programs. While LD vaginal states especially L. crispatus consistently correlate with improved implantation and live birth, the existence and clinical significance of a stable, distinct “endometrial microbiome” remains debated due to contamination risks. High-quality, contamination-controlled, prospective trials are urgently needed before routine microbiome-directed therapy is adopted in ART pathways.