In IVF cycles, embryonic chromosomal abnormalities, with aneuploidy being the main factor, are common causes of embryonic developmental arrest, repeated implantation failure, and multiple spontaneous miscarriages. Therefore, screening embryos for aneuploidy or genetic disorders before transfer to ensure that the transferred embryos are normal will improve the clinical outcome of IVF. At present, Shanghai Collective carries out PGS technology based on PGD. Usually, after blastocyst culture, the blastocysts cultured to the appropriate stage are micro-biopsied to take several trophectoderm cells for chromosome analysis, and the biopsied blastocysts are frozen. Normal blastocysts are thawed for transfer in a later recovery cycle.