Impact of chromosomal abnormalities on preimplantation embryo development

Abstract

Objectives: To evaluate the influence of numerical chromosomal abnormalities on preimplantation embryo development.

Methods: This study includes 6936 embryos from 1245 women undergoing preimplantation genetic diagnosis (PGD). Indications for aneuploidy screening were: recurrent miscarriages, implantation failure, severe male factor, advanced maternal age, and mixed causes. Embryo biopsy was performed on day 3, and embryos were co-cultured until day 5, when embryo transfer was performed.

Results: In the aneuploidy screening regimen, normal euploid embryos showed significantly higher blastocyst rates (68.2%) compared to chromosomally abnormal (42.8%, p < 0.0001) and mosaic (53.7%, p < 0.0001) embryos. Among aneuploid embryos for autosomes, higher blastocyst rates were observed in trisomies than monosomies, although only statistically significant in patients over 36 years of age (50.8 vs 38.9%; p < 0.0001). In contrast, in embryos with sex chromosomes aneuploidy, similar blastocyst rates were observed between trisomies and monosomy X.

Conclusion: Embryos with certain types of chromosomal abnormalities were negatively selected during preimplantation embryo development. Despite this selection, a remarkable percentage of chromosomally abnormal embryos can develop normally to blastocyst stage with high probability of implantation and pregnancy.