Abstract:

Objective: To explore the characteristics of vaginal microbiota in patients with repeated implantation failure (RIF). Methods: A total of 49 patients undergoing the frozen-thawed embryo transfer (FET) cycles were recruited. In the observation group, patients (n=29) with a history of RIF have failed pregnancy during the FET cycles. In the control group, patients (n=20) underwent the FET for the first time and achieved clinical pregnancy. In both groups, artificial hormone cycles were performed, and the top-quality blastocysts cultured on Day 5 were tranferred. Vaginal samples were collected on the FET day. Microbial diversity, microbial community composition and differential bacterial genera between the two groups were analyzed by 16S rRNA sequencing. The receiver operating characteristic (ROC) curve was used to analyze the diagnostic efficacy of the abundance of Lactobacillus for RIF. Results: The α diversity analysis showed that the microbial diversity (Shannon: P=0.049 8) and richness (Chao: P=0.047 1) of the observation group were significantly higher than those of the control group. The β diversity analysis showed that there was significant difference in the vaginal microbial community composition between the two groups (P=0.016). At the genus level, Lactobacillus was dominant in both groups. The abundance of Lactobacillus of the observation group was significantly lower than that of the control group, while the abundances of Acinetobacter and Pseudomonas of the observation group were significantly higher than those of the control group (LDA>3, P<0.05). The optimal cutoff value for diagnosing RIF with the abundance of Lactobacillus was 70%, and the area under curve (AUC) was 0.77. Conclusions: Vaginal microbiota was showed differences in RIF patients, including the decreased abundances of Lactobacillus. The low abundance of vaginal Lactobacillus may be related with the pathogenesis of RIF.

Key words: Repeated implantation failure, Vagina, Vaginal flora, 16S rRNA sequence, High throughput sequencing