A Study of the Effects of a Novel Ovarian Stimulation Regimen on Embryo Aneuploidy Rates in In Vitro Fertilization (IVF)

Background: By limiting the number of embryos transferred to the uterus to only a single embryo, the risk of multiple gestation can be reduced. In order to improve the effectiveness of single embryo transfer, the ability to select the embryo with the highest potential to develop into a healthy child is of vital importance. While embryos rated as high quality by standardized morphological assessment are associated with higher implantation and pregnancy rates, it is still not possible to predict with certainty which embryo will implant and has the highest potential to develop into a healthy child. An increasing body of evidence indicates that the incidence of chromosomal abnormalities in embryos is extremely high and good embryo morphology does not necessarily exclude an abnormal chromosomal constitution. Since aneuploidies are considered the main cause of embryonic wastage and loss, this phenomenon may be primarily responsible for the relatively poor pregnancy rates reported after IVF. The introduction of fluorescent in-situ hybridization (FISH) techniques for preimplantation genetic diagnosis has enabled screening of embryos for chromosomal aneuploidies before transfer. Preimplantation genetic screening (PGS) would be of special interest for couples that are thought to have a higher risk of developing chromosomally abnormal embryos, with the aim of improving their chances for an ongoing pregnancy after IVF. PGS is applied clinically in numerous IVF laboratories throughout the world, and high rates of chromosomal abnormalities have been reported in IVF derived embryos. However, a recent meta-analysis has shown that PGS is yet to have a significant impact on IVF outcomes. This may partly be explained by the fact that most aneuploidies observed at this stage originate during the first mitotic divisions of early preimplantation development, resulting in chromosomally mosaic embryos. If a chromosomally mosaic embryo is biopsied, this cell may not be representative for