Analysis of Factors Affecting Survival and Pregnancy Rate in Frozen-thawed Embryo Transfers

동결수정란 이식주기에서 수정란 융해 후 생존율과 임신율에 영향을 미치는 요인

Objective: The purpose of this study was to determine the important factors affecting survival and pregnancy rate in frozen-thawed embryo transfer cycles. Methods: we performed retrospective analysis in 738 cycles of frozen-thawed embryo transfers, in relation to the insemination methods, the freezing stage of embryo, patient's age, infertility factors and the origin of injected sperm in ICSI cycles. After conventional IVF or ICSI, the supernumerary PN stage zygotes or multicellular embryos were cryopreserved by slow freezing protocol with 1,2-propanediol (PROH) as a cryoprotectant. Results: The survival rates of thawed embryos were 69.3% (1585/2287) in conventional IVF group and 71.7% (1645/2295) in ICSI group. After frozen-thawed embryo transfers, 27.0% (92/341) and 32.0% (109/341) of pregnancy rates were achieved in conventional IVF and ICSI group, respectively. There were no significant difference in the survival and pregnancy rates according to the insemination methods, the freezing stage and patient's age. However, the pregnancy rate (36.2%) of male factor infertility was significantly higher than the tubal (27.2%) and other female factor infertility (22.9%). In ICSI group, the origin of injected sperm did not affect the outcome of frozen-thawed embryo transfer cycles. Conclusion: The present study demonstrates that acceptable clinical outcomes can be achieved after the transfer of frozen-thawed embryos regardless of the stage of embryos for freezing, the patient's age and the origin of injected sperm.