Introduction: The Dilemma of the Mosaic Embryo
For decades, preimplantation genetic testing for aneuploidy (PGT-A) has been a cornerstone of advanced reproductive technology, designed to identify chromosomal abnormalities that would otherwise lead to implantation failure or pregnancy loss. However, the transition from older technologies to highly sensitive next-generation sequencing (NGS) has introduced a complex clinical challenge: the detection of intermediate copy number (ICN) deviations, commonly referred to as mosaicism. While the industry has rushed to categorize these embryos, a critical question remains: does reporting these findings actually improve a patient’s chance of having a healthy baby? A landmark multisite study, recently published in the American Journal of Obstetrics and Gynecology, suggests that the answer may be a definitive no.
