Day 3 Embryo Biopsy Versus Blastocyst Biopsy in PGS Cases

Preimplantation genetic diagnosis (PGS) is a technique that allow us to improve the results of assisted reproduction techniques through the selection of embryos free of chromosomal abnormalities. At present, it has not been proved that the usage of PGS really improves the live birth rate in IVF cycles. However, it has been stated that the reason of not having better results when using PGS is that the methodology applied is not adequate. Several authors propose that the optimal methodology for PGS includes the application of comparative genomic hybridization (CGH) arrays for genetic testing and carrying out embryo biopsy at the blastocyst stage. Nevertheless, most IVF centres still applies the day 3 embryo biopsy as a daily routine. Despite this fact, there is a gradual transition towards the usage of blastocyst-stage biopsy instead of day 3 biopsy. The purpose of this clinical study is analysing the results of the IVF cycles with embryo biopsy for PGS. Live birth rates and other parameters as the pregnancy and implantation rates together with embryo quality will be analysed and compared between two groups of patients undergoing IVF cycles with PGS. In one group the biopsy will be applied in day 3 of the embryo development, while in the other group the embryo biopsy will be fulfilled at the blastocyst stage.