An increased incidence of aneuploid pregnancies has been reported in women of advanced maternal age, with higher miscarriage rates. Cytogenetic studies in preimplantation embryos have shown elevated aneuploidy rate, particularly in women over 38 years. For these reasons, PGS has been applied to these patients to improve ongoing implantation rates, and most importantly, to decrease the risk of further miscarriages and affected offspring. In the past two years, several RCT have raised the question whether PGS is benefitial or not in AMA patients.

In our experience, PGS outcome in these patients offers higher ongoing implantation rates than the previously published in RCT studies, where no benefits for PGS were found. In these papers, poor technical skills, as well as unclear patients selection could explain the reported lack of PGS benefits.

Therefore, the objective of the present RCT is to analyze the outcome of IVF cycles with and without PGS in two age groups:

• Patients 38-39 years of age: 200 cyles per arm reaching embryo transfer should be performed
• Patients 40-44 years of age: 120 cycles per arm reaching embryo transfer Sample size has been calculated according to our retrospective experience with higher differences in ongoing implantation rates between cycles with and without PGS in patients of 40-44 years of age. In all patients embryo transfer will be performed on day 5. In the PGS group one cell will be biopsy in embryos with ≥5 cells on day-3 and chromosomes 13, 15, 17, 18, 21, 22, X and Y will be analyzed in two rounds. In the third round, nuclei with undoubtful or non-conclusive results will be analyzed using subtelomeric probes.