A pilot study and case reports on endometrial microbiota and pregnancy outcome: An analysis using 16S rRNA gene sequencing among IVF patients, and trial therapeutic intervention for dysbiotic endometrium

Purpose The present study aimed to analyze the pregnancy outcomes of IVF patients presenting Lactobacillus-dominated microbiota (LDM) or non-Lactobacillus-dominated microbiota (NLDM) of their endometrium and to report cases who were treated for NLDM concurrently with antibiotics and prebiotic/probiotic supplements in a Japanese infertile population. Methods Ninety-two IVF patients were recruited from August 2017 to March 2018. Endometrial fluid samples for sequencing were collected using an IUI catheter. The bacterial status of the endometrium and the pregnancy outcomes were analyzed. For cases with NLDM, antibiotics and prebiotics/probiotics were administered according to their individual microbial conditions. Results Forty-seven cases (51.1%) presented LDM and 45 cases (48.9%) presented NLDM at initial analysis. Nine Patients with NLDM were treated by antibiotics and prebiotics/probiotics, and successfully became Lactobacillus-dominant. Pregnancy rates by single vitrified-warmed blastocyst transfers were higher in the LDM group (58.9% per patient and 36.3% per FBT) than in the NLDM group (47.2% per patient and 34.7% per FBT) but not significantly different. Conclusion The results of this study could not necessarily prove the clear benefit of establishing Lactobacillus-dominated endometrium in terms of pregnancy outcome, but there is significance in searching for endometrial microbial status of infertile patients and recovering Lactobacillus-dominated endometrium might benefit implantation.