Differential characteristics of vaginal versus endometrial microbiota in patients with implantation failure and recurrent miscarriage

Abnormal female reproductive tract microbiota are associated with gynecological disorders such as endometriosis or chronic endometritis and may affect reproductive outcomes. However, the differential diagnostic utility of the vaginal or the endometrial microbiome and the impact of important technical covariates such as the choice of hypervariable regions for 16S rDNA sequencing remain to be characterized. In a retrospective study of patients diagnosed with repeated implantation failure (RIF) and/or recurrent miscarriage (RM) in an IVF outpatient clinic, we compared microbiome composition based on V1-V2 rDNA sequencing between matched vaginal smear and endometrial pipelle-obtained biopsy samples (n = 71); in a sub-group (n= 61), we carried out a comparison between V1-V2 and V2-V3 rDNA sequencing.