PGDIS position statement on the transfer of mosaic embryos 2021

Area of Science:

• Reproductive Medicine
• Genetics
• Embryology

Background:

• Preimplantation genetic testing for aneuploidy (PGT-A) aids in selecting embryos for in vitro fertilization (IVF).
• Emerging technologies reveal mosaic embryos with intermediate chromosome copy number variations in the trophectoderm.
• Mosaic embryos may represent the sole transfer option for certain patients.

Purpose of the Study:

• To provide guidance on the clinical utility and transfer of mosaic embryos.
• To assist laboratories, clinics, clinicians, and counselors in managing mosaic embryo cases.
• To inform discussions regarding the risks and benefits of transferring mosaic embryos.

Main Methods:

• Review of recent data on mosaic embryo transfer outcomes.
• Analysis of risks associated with varying levels of mosaicism.
• Development of a position statement for clinical practice.

Main Results:

• Mosaic embryo transfer is not associated with increased abnormal birth outcomes.
• Higher levels of mosaicism correlate with increased implantation failure and miscarriage rates.
• Mosaic embryos can be transferred, particularly when they are the only option.

Conclusions:

• Mosaic embryos require careful consideration in IVF protocols.
• Clinical management should balance the potential for transfer against associated reproductive risks.
• Further research is needed to optimize outcomes for mosaic embryo transfers.