Chromosomal aneuploidy is the leading cause of implantation failure and first-trimester miscarriage, and its incidence rises sharply with maternal age. By identifying which embryos are chromosomally normal before transfer, Preimplantation Genetic Testing for Aneuploidy allows clinicians to prioritize the embryo(s) with the highest biological likelihood of implanting and progressing to a healthy pregnancy, rather than selecting based on morphology (appearance) alone.