P-240 High mitochondrial DNA content in Day6 blastocyst may impair ongoing pregnancy rate

Abstract Study question Is there an association between mitochondrial DNA (mtDNA) content and Ongoing Pregnancy Rate (OPR) in D5 or D6 euploid blastocyst? Summary answer Day6 OPR is decreased high mtDNA blastocyst. Day5 levels are independent of maternal age standard morphology. What known already Preimplantation development energy-demanding process ATP production crucial for cellular activity fast replicating cells. Mitochondrial preimplantation embryo has been proposed as a marker potential term viability implantation success though the dynamics distribution mitochondria human still debated. In recent years, it suggested that low were associated with chromosomal complement higher rate while other studies failed to find correlation reproductive outcome. design, size, duration This study retrospective cohort analysis from 2020 2022 including 343 187 single blastocyst transfer. Primary endpoint was beyond pregnancy week 16. frozen-thawed transfer divided based on four groups: Day5-high, Day5-low, D6-high, D6-low. Secondary endpoints relationship content, morphology all obtained blastocysts. Statistical differences compared by Chi-Square test. Participants/materials, setting, methods 771 couples performed IVF cycles next-generation sequencing (NGS)-preimplantation genetic testing aneuploidy (PGT-A) (age 19-47yrs; Mean 37.8yrs). Following culture sequential media 700 copy number variation examined simultaneously next generation (NGS) methodology. numbers observed ratios sequence coverages nuclear DNA. Main results role chance our clinical setting similar vs. transfers (55% 49% n.s.). However when considered D6-low comparable D5-high (57.3%; 53.3%; 57,3% respectively n.s.) D6-high yield significantly (31,2% p < 0.05). When stratified only Advanced Maternal Age (AMA) patients ( > = 38yrs) showed this decrease at significant level (Day6 20% 0,05).This result transferred despite high:low ratio biopsied constant (1:1) (47%-53%) markedly (1:4) (25%-75%) either overall younger (n.s.) AMA (n.s.). Moreover evaluated according Gardner classification criteria top, fair poor quality blastocysts display same 1:1 1:4 Day 6 patients. Hence, patients’ quality. The origin could therefore depend Day6-high ultimately available each patient. Limitations, reasons caution Due small blastocyst, larger sample size required confirm these preliminary findings. Moreover, nature may introduce some bias mainly characteristics strategy selected Wider implications findings While Day5-high persistence hamper their potential. Our help select maximize success. should be preferred whenever choice possible. Trial registration Not Applicable