Recurrent Implantation Failure and the Gut–Endometrium Axis: A Pilot Study on Microbiota Crosstalk
Year: 2026
Type: article
Study design: Observational Study
Abstract: Objective: To assess gut and endometrial microbiota simultaneously in women with unexplained recurrent implantation failure (RIF) and explore the hypothesis of a gut-endometrium microbial axis. Study design: This monocentric observational pilot study included women aged 38 years or younger with RIF and a normal uterine cavity. Paired fecal and endometrial samples were collected on the same day and analyzed by 16S rRNA gene sequencing. Relative abundances of major phyla and alpha-diversity indices were compared between compartments. Results: Twenty-one women were included. Chronic endometritis was documented hysteroscopically in all cases. Gut dysbiosis was observed in 20/21 patients (95.2%), whereas endometrial dysbiosis was found in 16/21 (76.2%); crude agreement between compartments was 71.4%. The intestinal microbiota was dominated by Bacteroidetes (52.8% ± 14.9%) and Firmicutes (33.3% ± 11.0%), whereas the endometrial microbiota was enriched in Firmicutes (64.5% ± 33.5%) and Proteobacteria (30.9% ± 32.3%). Bacteroidetes were significantly more abundant in fecal than endometrial samples (p < 0.001), while Firmicutes were significantly enriched in the endometrium (p = 0.001). All alpha-diversity indices were significantly higher in feces, indicating greater microbial richness and complexity in the gut. Conclusions: In women with RIF, gut and endometrial dysbiosis frequently coexist and show relevant concordance. These data support the hypothesis that endometrial dysbiosis may reflect a broader systemic microbial imbalance rather than an isolated uterine disorder.
Source: Journal of Clinical Medicine
DOI: 10.3390/jcm15197620
Language: English
Topic: Gut microbiota and health
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W7170158719