Aneuploidy rate in embryos with accelerated cleavage (day 3) in a PGS program

Abstract

This work aims to establish a difference in aneuploidy rate in blastocysts generated from embryos with accelerated cleavage at day 3 compared to normally developed embryos Comparative cohort study Fifty-seven PGS cycles (50 patients) that were performed at CEGYR from June 2013 to December 2014 were considered. The average women and men age was 37.9±3.8 and 39.9±4.1 y/o, respectively. A total of 578 MII oocytes were obtained, with a 77.9% fertilization rate. From 450 fertilized oocytes, 446 (99.1%) cleaved at 48 hours, at 72 hours the cleavage rate was 100% (450). Of total cleaved embryos (72 hs), 52% (234) reached the blastocyst stage.For the analysis-interpretation of the results, 3 groups were considered according to the number of cells at day 3: (A) ≥10 cells (accelerated-cleavage), (B) =8 cells embryos from a cohort with accelerated embryos, and (C) =8 cells embryos from a cohort without accelerated embryos. Embryos that reached the blastocyst stage, either at day 5 or 6, were classified in: good, regular and low quality (degree of expansion, inner cell mass-trophectoderm and blastocoel). Blastocysts biopsies were analyzed by aCGH. In group A, the amount of embryos that reached the blastocyst stage was significantly higher (84.1%) compared than Group B (58.8%) and C (67.6%). Between groups B and C there were no significant differences. The rate of euploid blastocysts in group A was 64.9%, significantly higher than groups B (43.3%) and C (43.0%). No difference in aneuploidy rate was evidenced between day 5 or 6 blastocysts. In group A, there were no differences in blastocyst-quality and aneuploidy rate. However, in group B and C, blastocysts with better morphology correlated with lower aneuploidy rates. In our preliminary experience, we can conclude that the number of cells on day 3 could help to understand the prognosis of blastocysts aneuploidy rate on day 5 or 6. The embryos at day 3 with accelerated behavior, which usually are not preferably chosen to transfer, have lower aneuploidy rates than embryos with normal cleavage.