P-365 The composition of the endometrial microbiota, as determined by MicroBioMap®, significantly affects clinical outcomes in assisted reproduction treatments

Abstract Study question How does the presence of specific pathogenic or health-promoting microbial species in endometrium relate to female fertility assisted reproduction treatments (ART)? Summary answer Detection endometrial pathogens using MicroBioMap® is associated with poor ART outcomes, whereas sterile endometria show highest pregnancy and live birth rates. What known already Vaginal eubiosis characterised by low diversity dominance Lactobacillus, which displays bioregulatory functions prevents growth microorganisms. dysbiosis directly linked infertility outcomes. However, microbiota composition its role are more controversial. Robust reports that chronic endometritis (CE) highly prevalent among infertile patients, whose outcomes improve after antibiotic treatment. Lactobacillus this compartment, whether it also functions, if essential beneficial for women undergoing ART, still unclear. design, size, duration This a case-control retrospective study analysing window implantation (WOI) 456 IVF cycles egg donation regimes with/without PGT-A (177 163 respectively), their own eggs (91 25 between March 2016 April 2021 IVF-Life Alicante (Spain). results single embryo transfer (sET) patients different profiles were compared. Participants/materials, setting, methods Presence 18 CE 4 was determined high-throughput qPCR (MicroBioMap®) samples obtained during WOI (determined ER Map® receptivity test) hormone replacement therapy cycle. Clinical (clinical pregnancy, CP; birth, LB) sETs performed (guided Map®) compared relation profile. In cycles, ploidy NGS (VeriSeq-MiSeq) before sET. Main chance According profile detected MicroBioMap®, categorised as i) only (L, n = 199), ii) Pathogens (P, 56), iii) + (L+P, 59) iv) Undetected (U, 142). Absence microorganisms significantly success. U-patients showed higher CP (64.2% vs 50.8%, Fisheŕs exact p=0.046) LB rates (52.9% 37.2%, p=0.03) euploid sET than These differences pronounced receiving donor (CP 70.2% p=0.026; 59.5% 40.2%, p=0.046). isolation detrimental effect U-environments. A trend towards statistical significance detected, L-patients showing lower (38.8% 52.9%; p 0.084). reduced success P-patients had 41.2%, p=0.038) U-patients, (70.2% 36%, p=0.006) (59.5% 21.7%, p=0.004) eggs. Interestingly, pathogen-positive seemed pathogen-dominated 56.7% 42.2%; 41.7% 31%). Limitations, reasons caution study. Randomised-control trials, non-selection studies and/or other investigations including antimicrobial needed confirm these extent any clinical benefits. Endometrial biopsies transcervically. Although utmost care taken, risk contamination from genital tract cannot be completely excluded. Wider implications findings Our suggest provide best conditions pregnancy. might not could even found isolation. bioregulator co-colonise tissue. Trial registration number Not applicable