Effect of repeated cryopreservation on human embryo developmental potential

Area of Science:

• Reproductive Medicine
• Embryology
• Cryobiology

Background:

• Cryopreservation of surplus embryos is common practice in assisted reproductive technology.
• Vitrification has become a preferred method for embryo cryopreservation due to high survival rates.

Purpose of the Study:

• To evaluate pregnancy and perinatal outcomes of human blastocysts derived from twice-cryopreserved (vitrified-warmed) day 3 embryos.
• To compare outcomes between twice-cryopreserved embryos and fresh embryos (control group).

Main Methods:

• Retrospective cohort study of 571 vitrified-warmed blastocyst transfer cycles.
• Embryos were either twice-cryopreserved (slowly frozen-thawed day 3 embryos) or fresh, then cultured to blastocyst stage.

Main Results:

• No significant differences in patient age, BMI, endometrial thickness, blastocyst development, or embryo transfer numbers.
• Clinical pregnancy and implantation rates were similar between twice-cryopreserved and control groups.
• Significantly higher miscarriage rate (33.93% vs. 19.07%) and lower live birth rate (29.13% vs. 39.18%) in the twice-cryopreserved group.

Conclusions:

• Transfer of twice-cryopreserved human embryos can yield acceptable clinical pregnancy outcomes.
• While neonatal outcomes are not impacted, the increased risk of pregnancy loss warrants further investigation.
• Repeated cryopreservation requires careful consideration due to potential impacts on pregnancy viability.