Current IVF practice includes the transfer of more than one embryo to achieve a “reasonable” pregnancy rate. During the early days of IVF, the 3, 4 or even 5 embryos were transferred in every procedure. Implantation rates were very low and embryos preservation procedures were inefficient.
However, it is possible in the 21 st century to select the right embryo to be transferred by using both morphokinetic and genetic criteria. Thus, if we are able to choose the genetically normal blastocyst (a 5-day embryo) the implantation rates increase. By using PGS we do not increase the absolute number of pregnancies but we augment the pregnancy rate per transfer (reducing the number of embryo transfers without the achievement of an ongoing pregnancy). Indeed, this was the statement of Laura Rienzi in her debate in favor of PGS use and the main result of the poster defended by Reproducción Bilbao at ESHRE meeting.