Aneuploidy is the term associated with an abnormal number of chromosomes found in a cell within an early human embryo. This term literally means not or without the correct number of chromosomes. A genetically normal embryo is made up of cells that each contain 46 chromosomes, numbered 1-22 (autosomes) plus the sex chromosomes X and Y. Embryos with the correct number of chromosomes are also called euploid embryos. Unfortunately, aneuploid embryos do not physically look any different than euploid embryos so without preimplantation genetic testing for aneuploidy (PGT-A), aneuploid embryos can and will be transferred and these embryos have been shown to fail implantation in about 96% of the cases1. It is therefore important to identify and selectively transfer euploid embryos which have been shown to have a very high chance of successful implantation and pregnancy.
As the graph (right) shows2, the incidence of embryo aneuploidy increases with maternal age from approximately 30% at age 30-34 up to almost 80% at age 41-42! This is a major reason for the decreasing expectation of live birth per treatment cycle associated with maternal age. In this same chart you will notice that implantation rate does not decrease with maternal age when selectively transferring euploid embryos during IVF cycles.