P-473 The reproductive performance of euploid blastocysts declines after each consecutive embryo transfer: The pendulum is swinging back?

Abstract Study question the impact of euploid blastocysts on reproductive performance by association between the number of previous failed IVF cycles and live birth rate per transfer Summary answer Our findings suggest a negative association between the number of previous failed IVF cycles per euploid transfers. implantation rates decreased following each consecutive FE-ET cycles What is known already In assisted reproductive technologies, implantation failure presents a challenging clinical dilemma since its underlying etiology is unknown. Implantation is a very complex process which involves a variety of factors related to the embryo, endometrium, and immune system (Fox et al. 2016). Therefore, implantation failure is also a complex pathological condition that involve both embryonic defects and/or endometrial dysfunctions (Das et al.2012). This situation poses a therapeutic dilemma. Hence implantation failure etiologies and treatments remain unresolved. which results in ongoing debate over whether embryonic chromosomal aneuploidy is a major contributor or within the endometrium itself. Study design, size, duration This observational cohort study included 387 patients undergoing euploid embryo transfer between January 2015 and until October 2022. Participants/materials, setting, methods Participants: Women with an anatomically normal uterus who underwent autologous vitrified-warmed euploid blastocyst transfer (Frozen Euploid Embryo Transfer: FE-ET) cycles were included in the study. Setting: Fertility center at a university-affiliated public hospital. Intervention(s): Trophectoderm biopsy and comprehensive preimplantation 24-chromosome analysis using Next Generation Sequencing (NGS). Main Outcome Measure(s): Cumulative outcomes from these cycles were analyzed. A logistic regression model was used to assess the differences in outcomes between the first, second, and third FE-ET. Main results and the role of chance The mean age of the patient population under investigation was 33.4 ± 5.3 years. Maternal age at oocyte retrieval was negatively associated with the mean euploidy rate per cohort of biopsied blastocysts from each patient (m-ER). The m-ER did not show any association with the number of previous failed IVF cycles (0/1-2/≥3) among different ranges of maternal age at oocyte retrieval (≤30/31-35/36-39/≥40). The transfer of the first single vitrified-warmed euploid blastocyst was associated with an implantation rate (IR) of 47%, a miscarriage rate of 17