Vaginal microbiota in assisted reproduction: determinants, dynamics, and impact on clinical outcomes

The vaginal microbiota (VMB), predominantly composed of Lactobacillus genus, plays a crucial role in maintaining female reproductive health through acid production, immune modulation, and protection against pathogens. However, substantial inter-individual variability exists in its composition and stability. In assisted reproduction, the vaginal microenvironment is increasingly recognized as an important factor influencing embryo implantation and pregnancy outcomes. Emerging evidence suggests that the composition and dynamics of the vaginal microbiome are not only predictive biomarkers but also potential regulatory targets influencing assisted reproduction outcomes. This review outlines vaginal microbial community types, key behavioral and host-related determinants, and their links to ART outcomes. We also discuss current limitations, including methodological heterogeneity, unclear causal mechanisms, and the lack of standardized intervention strategies. Finally, we highlight the need for longitudinal and multi-omics studies to support the clinical translation of vaginal microbiome research in reproductive medicine.