ABSTRACT
INTRODUCTION Blastocyst culture and transfer are strongly desired, as they allow for increased embryo selection and consequently lead to signicantly improved implantation and live birth rates (1). In contrast, cleavage-stage transfer programs are now more oen nding themselves at a disadvantage. Transferring at the cleavage stage mostly necessitates the transfer of multiple embryos to be competitive and, as a result, is plagued with multiple implantations. Furthermore, the practice of transferring multiple cleavage-stage embryos does not easily lead to higher live birth rates anymore.
