Commentary on two recently published formal guidelines on management of "mosaic" embryos after preimplantation genetic testing for aneuploidy (PGT-A). - Gleicher, Norbert; Barad, David H.; Ben-Rafael, Zion; Glujovsky, Demian; Mochizuki, Lyka; Modi, Deepak; Murtinger, Maximillian; Patrizio, Pasquale; Orvieto, Raoul; Takahashi, Shizuko; Weghofer, Andrea; Ziebe, Søren (Reproductive Biology & Endocrinology, 2021)