High pregnancy rate after early human embryo freezing

Area of Science:

• Reproductive biology
• Cryobiology
• Embryology

Background:

• In vitro fertilization (IVF) has advanced reproductive medicine.
• Cryopreservation of human embryos is crucial for IVF success rates.
• Optimizing cryopreservation techniques is essential for improving outcomes.

Purpose of the Study:

• To evaluate the efficacy of cryopreservation using 1,2-propanediol for human embryos.
• To determine factors affecting embryo survival post-thaw.
• To assess pregnancy rates following frozen embryo transfer (ET).

Main Methods:

• Human embryos were cryopreserved using 1,2-propanediol.
• Embryo survival was assessed based on nuclear presence and cell number.
• Frozen embryos (1-2 days post-IVF) were thawed and transferred.

Main Results:

• Embryo survival was linked to nuclear presence and inversely related to cell number.
• No survival was observed in embryos frozen 3-4 days post-IVF.
• A 22% pregnancy rate was achieved after ET of 1-2 day frozen embryos (7/32 patients).
• One pregnancy resulted from a thawed 1-cell pronucleated embryo transfer.

Conclusions:

• Cryopreservation of early human embryos (1-2 days post-IVF) with 1,2-propanediol is effective.
• Cryopreservation and ET can potentially match natural fertility liveborn rates in IVF programs.
• Further research into cryopreservation of later-stage embryos is warranted.