In this article we present a new approach for the aneuploidy testing of embryos without the need for embryo biopsy. This is a non-invasive approach that would allow better selection of the embryo in an IVF cycle, to improve implantation and decrease miscarriage rates. Special care should be taken to avoid misdiagnosis due to the presence of DNA from the cumulus cells surrounding the oocyte, but results are encouraging.

Preimplantation genetic testing has been used clinically for 25 years. The technology has changed during these years as well as the indications. Advanced maternal age is one of the most common indications. In this randomized controlled trial, we investigated patients between 38-41 years of age undergoing IVF and compared the clinical outcome of those with blastocyst transfer in whom preimplantation genetic testing was performed to those with blastocyst transfer (control group). The results show an increase in delivery rates per transfer, a reduction in miscarriage rates and time to pregnancy for the PGTA group with similar costs for each treatment arm. Cumulative pregnancy rates after consecutive cryotransfer were not significantly different between the two groups.

This is a review article to describe the incidence of mosaicism in different stages of embryo development, from the preimplantation stage to early pregnancies and livebirths. Despite mosaicism is a phenomenon that is present in the embryo from the two-cells stagethe real incidence is under discussion. To estimate the real percentage it should be considered the impact of the biopsy of the trophectoderm and the number of cells removed as well the technology of next generation sequencing employed.

New technologies applied to the field of preimplantation genetic testing have allowed the possibility of identifying not only whole chromosome aneuploidies, but also small duplications/deletions, called segmental aneuploidies, bigger than 6 Mb. The origin of these abnormalities should be mostly mitotic, despite some of them being identified in all of the cells from a blastocyst fixed and analyzed by FISH.

Patients undergoing IVF treatment can have implantation rates around 50-60% but even after transfer of euploid embryos, some of them do not get pregnant. It is fully accepted that some cases of implantation failure have an origin in uterine receptivity, but the energy of the embryo and oxidative stress could also impact embryo viability. The aim of this article is to identify a novel biomarker of the fitness of the embryo, the ratio of mitochondrial DNA present in a day-3 or trophectoderm biopsy and its relationship to implantation rates. We showed that a higher mitochondrial DNA ratio was related to lower implantation.