Association between endometrial microbiome and implantation success in women with frozen embryo transfer: results of a prospective cohort study

The aim of this prospective study was to compare the endometrial microbiome between pregnant and non-pregnant women after frozen embryo transfer (FET) with euploid embryos. Endometrial biopsies were collected from 30 during mid-luteal phase in a natural cycle. FET performed embryos up 3 months biopsy. microbiota composition analysed using 16S rRNA (v4-v5 region) next generation sequencing (NGS). analysis different clinical outcomes biopsy (no pregnancy (n = 14), ultrasound confirmed 16)) revealed differences composition. In total, 271 distinct bacterial species 668 genera identified. number unique found 62 (22.88%), while patients who became it 39 (14.39%). Among them, bacteria high frequency occurrence such as Bacteroides spp., Cutibacterium granulosum, Isoptericola Acetomicrobium Marivivens spp. Syntrophomonas only patients, Bosea present women. relative abundance that Lactobacillus genus not significantly studied groups. contrast, Serratia marcescens, Staphylococcus Glutamicibacter Delftia enriched group. conclusion, specific taxa had higher endometrium implantation failure We hypothesize an appropriate treatment for optimization content diagnosed dysbiosis could be beneficial improvement rates.