[Dynamics of vaginal microbiota in women of reproductive age during the menstrual cycle].

Objective: To investigate the dynamic changes of vaginal microbiota in different phases of menstrual cycle in healthy Chinese women of childbearing age. Methods: A total of 11 healthy women of childbearing age with regular menstruation, who had physical examination in the Gynecology Clinic of Beijing Obstetrics and Gynecology Hospital from September to December 2020 were randomly selected as research subjects. Vaginal secretions were collected during menstrual phase (2nd-3rd day), mid-follicular phase (7th-8th day), and mid-luteal phase (21st-22nd day) for microbiota analysis through metagenomic sequencing. Results: (1) Vaginal microbiota species were the most diverse in menstrual phase and the least in follicular phase, observing dominant vaginal bacteria gradually changing to Lactobacillus from menstrual phase to follicular phase and then to luteal phase. (2) The dynamic evolution of vaginal microbiota from menstrual phase to follicular phase and then to luteal phase was divided into: no change in dominant bacteria, replacement of dominant bacteria, changes in the proportion of dominant bacteria, and recurrence of dominant bacteria (non-Lactobacillus-dominance appeared again in luteal phase after returning to normal Lactobacillus-dominance in follicular phase). (3) Prevotella, especially Prevotella_bivia, was significantly higher during menstrual phase. Conclusions: Healthy vaginal microbiota should be relatively stable, but also have the ability of dynamic change and self-recovery. Prevotella plays a central role among opportunistic pathogens in the vagina, whose function remains to be investigated.