Inclusion Criteria:  Patients undergoing IVF/ICSI-treatment with controlled ovarian stimulation with gonadotrophins and the intention to treat by transfer of a single day 5 fresh blastocyst on day 5. At least two good quality blastocysts (GQB) on day 5 (3BB or better on the Gardner scale), originating from normally fertilized oocytes (2PN).  Exclusion Criteria:  Previous participation in this RCT Concurrent participation in another investigation Intention to perform any form of preimplantation genetic testing Fertility preservation Planned transfer on day 2-4 Female age >42 years A reduced likelihood of obtaining two good quality blastocysts on day 5 as evidenced by an AFC <5 (if available, AFC=antral follicle count)