The contribution of embryo cryopreservation to in-vitro fertilization/gamete intra-Fallopian transfer: 8 years experience

Abstract

In this paper, the authors summarized their experience with embryo cryopreservation over an 8-year period. The results, therefore, reflect the long-term benefit of embryo cryopreservation to the overall in-vitro fertilization/gamete intra-Fallopian transfer (IVF/GIFT) programme and to the women who had embryos cryopreserved. The stable survival rate of thawed embryos and pregnancy rate, especially over the past 4 years, suggests that the results can reliably be used to evaluate the efficacy of the embryo cryopreservation programme. The ongoing pregnancy rate of frozen/thawed embryo transfer is 10.9%, comparable with the ongoing pregnancy rate of fresh IVF/embryo transfer in our unit over the same period. In addition to those factors known to affect the pregnancy rate in fresh IVF/GIFT cycles, such as age of the recipients and number of embryos transferred, the major factor affecting the efficacy of the cryopreservation programme is the number of oocytes retrieved in the initial stimulation cycle, and the number of embryos available for cryopreservation. The storage time of cryopreserved embryos will also have a significant effect on the realization of the total potential of embryo cryopreservation. Overall the contribution of cryopreservation to our IVF/GIFT programme is substantial, increasing pregnancy rate by 4%, while the greater net benefit, of course, is for the women who had embryos cryopreserved (pregnancy rate increased by 7%), especially for those who returned for frozen/thawed embryo transfer cycles (pregnancy rate increased by 11%).