2. Frozen group: All embryos will be hatched on day 3. Patients will have hatching blastocysts (*) biopsied on day 5 or day 6, embryos will then be vitrified, analyzed by NGS, and will have one or two euploid embryo(s) thawed and transferred on a FET cycle, before noon. If more than two euploid blastocysts are available the one(s) to be transferred will be selected based on morphology (*).