THE MORPHOLOGY OF MOSAICISM: CHARACTERIZING LOW- AND HIGH-LEVEL MOSAIC EMBRYOS COMPARED TO EUPLOID EMBRYOS

The developmental patterns of mosaic embryos have yet to be understood.1 aim this study is determine whether low and high level differ from euploid in morphologic characteristics. included ovarian stimulation cycles a single academic institution with preimplantation genetic testing for aneuploidy (PGT-A) January 2020-March 2021. Trophectoderm (TE) biopsies were analyzed using modified FAST-SeqS NGS-based PGT method bioinformatics pipeline. Embryos classified as if the TE biopsy result contained <20% mosaicism; 20-40%; 41-80%; aneuploid >80%. association between morphology (high quality overall grade (≥4BB) expansion (Exp), inner cell mass (ICM) grade, trophectoderm grade) presence mosaicism compared chi-square multivariable logistic regression. A total 7872 included, which 4074 (51.8%) euploid, 2763 (35.1%) 1035 (13.1%) mosaic. proportion graded was significantly lower than (63.5% vs. 72.1%, p<.0001) higher 52.3%, p<.0001). Controlling age day biopsy, associated odds euploidy (aOR=0.71, 95% CI 0.61-0.82, High ICM grades embryo (ICM C: aOR=0.79, 0.63-0.99, p=.04; aOR=0.55, 0.46-0.66, p<.0001), while Exp not. Analyzing revealed that (aOR=1.33, 1.02-1.73, p=.03), (6 4: aOR=1.53, 1.04-2.23, p=.03) ( aOR=1.47, 1.07-2.02, p=.02) more likely mosaicism, not mosaicism. When comparing mosaics respectively embryos, poor (TE C A: aOR 1.56, 1.25-1.92, There no differences embryos. Exp, ICM, (Exp 4 6: aOR=1.38, 1.01-1.88, p=.046; aOR=1.39, 1.01-1.92, p=.049; 2.27, 1.76-2.94, Mosaic receive dose-dependent relationship, having grading only.