Comparison of Clinical Outcome after Transfer of Cryopreserved and Fresh Embryos Originating from Conventional IVF andICSI

Objectives To evaluate the impact of cryopreservation on early cleavage stage (d 2) embryos Methods This was a retrospective study. Embryo survival rate, implantation rates and clinical pregnancy rates per transfer from fresh and cryopreserved cycles were analyzed. Results From January to December, 2002, in a total of 628 thawing cycles in which 1 876 embryos were thawed, the embryo survival rate was similar between the IVF and ICSI group (88.09% and 88.95%, respectively). There was no significant difference in implantation rates both between the frozen and fresh IVF groups (19.19% and 21.07%, respectively) and between the frozen and fresh ICSI groups (15.22% and 15.64%, respectively), but there were significant differences either between frozen IVF and frozen ICSI groups (P<0.05) or between fresh IVF and fresh ICSI groups (P<0.01). The clinical preg- nancy rates in the frozen and fresh IVF groups were 45.86% and 43.43%, respec- tively (P>0.05). The clinical pregnancy rate of the frozen ICSI group was 42.07%, slightly higher than that of fresh ICSI (35.43%), but the difference was not significant (P>0.05). The clinical pregnancy rate between fresh IVF and fresh ICSI was signifi- cantly different (P<0.05). Conclusion The present study indicated that frozen-thawed embryos at early cleavage stage had equivalent pregnancy rates as that of fresh embryos.