O-004 Self-correction in human preimplantation development: What do we know?

Abstract textRecent advances in preimplantation genetic testing for aneuploidy (PGT-A) and time-lapse imaging have improved our understanding of the early human embryo confirming the variable patterns of development and chromosomal status. Aneuploidy is common and increased sensitivity in PGT-A allows the non-binary reporting of euploid-aneuploid mosaicism. The PGT-A result is the inference of the biopsied embryo ’s ploidy status at a point in time, by assessment of a small percentage of cells, and, whilst concordance with the rest of the embryo is high; it is not absolute.Many reports have demonstrated that, with the transfer of embryos with increasing severity and complexity of mosaicism, comes compromis ed implantation, reduced ongoing pregnancy rates and increased miscarriage rates. Segmental mosaic embryos have been reported to have slightly reduced implantation potential compared with euploid counterparts. However, complex mosaic embryos are widely reported to result in severely reduced implanta tion success, if transferred.Outside of PGT-A treatment cycles, undoubtedly fertility clinics are unwittingly transferring mosaic and aneuploid embryos daily, with variable success. The transfer of embryos in which mosaicism has been detected, although associated with lower implantation and higher m iscarriage rates than euploid embryos, can lead to normal pregnancies and healthy births. We know that the placenta can harbour chromosomal aberrations which are absent from the fe...
Source: Human Reproduction - Category: Reproduction Medicine Source Type: research