Ambient temperature affects the composition of the vaginal microbiome, and temperature-sensitive vaginal microbes influence assisted reproductive technology outcomes.

OBJECTIVE: To investigate the influence of environmental factors on the composition and structure of the vaginal microbiome and to explore the interaction among environmental factors, vaginal microbiome, and outcomes of assisted reproductive technology (ART). METHODS: Adonis test was utilized to evaluate the impact of 33 host/environmental variables on vaginal microbiome. Distributed lag nonlinear model analysis (DLNM), Mfuzz analysis, and linear mixed effect model were employed to establish the correlations between ambient temperature and vaginal microbes. RESULTS: Ambient temperature was one of the most important environmental factors associated with vaginal microbiome. As the temperature increased, succession of vaginal microbes showed four patterns of abundance variation. Furthermore, a group of vaginal microbes showed a preference for certain temperatures, and these microbes' varying interactions partly drove the shift of microbial networks at different temperatures. The community assembly process of vaginal microbiome deviated from neutral model and exposure to ambient temperature did not affect the role of stochastic processes in shaping vaginal microbial community. Notably, vaginal microbiome prior to embryo transfer was significantly associated with preterm birth. Preterm women exhibited higher abundance of Lactobacillus iners and lower abundance of Lactobacillus crispatus. CONCLUSIONS: Ambient temperature change can affect the structure and composition of the vaginal microbiome and correlate with the abundance of certain vaginal microbes. Temperature-sensitive vaginal bacteria may affect the risk of future preterm births. Video Abstract.