Implantation potential of mosaic embryos

Area of Science:

• Reproductive Biology
• Genetics
• Embryology

Background:

• Chromosomal mosaicism is frequently observed in human embryos developed through in vitro fertilization (IVF).
• The relationship between mosaicism in the trophoectoderm and inner cell mass, its underlying mechanisms, and impact on implantation remain unclear.
• Understanding mosaicism is crucial for improving IVF success rates.

Purpose of the Study:

• To investigate the prevalence of chromosomal mosaicism in human IVF embryos.
• To analyze the association between mosaicism and IVF cycle outcomes, including clinical pregnancy and miscarriage rates.
• To evaluate the potential for mosaic embryos to lead to successful full-term pregnancies.

Main Methods:

• Retrospective analysis of array-comparative genomic hybridization (array-CGH) data from 1,362 trophoectoderm biopsies.
• Categorization of blastocysts into mosaic or euploid based on array-CGH results.
• Comparison of clinical pregnancy rates and miscarriage rates between cycles involving transfer of mosaic versus euploid embryos.

Main Results:

• Chromosomal mosaicism was detected in 13.4% (183 out of 1,362) of blastocysts analyzed.
• A non-statistically significant decrease in clinical pregnancy rate was observed for mosaic embryo transfers (26.9%) compared to euploid embryo transfers (40.2%).
• A trend towards increased biochemical miscarriage rates was noted in cycles with mosaic embryo transfers (21.2%) versus euploid embryo transfers (12.3%).

Conclusions:

• The transfer of some mosaic embryos can result in successful full-term pregnancies.
• While trends suggest potential negative impacts on pregnancy and miscarriage rates, further investigation is warranted.
• Additional research is essential to fully elucidate the effects of embryo mosaicism on IVF outcomes.