Title : Comparison of chemical pregnancy results from the transfer of day-3 and day-4 fresh and cryopreserved cycles obtained by the microinjection method
Abstract:
Backgrounds: With the advancement in the embryo culture media which supports nutrient requirements of embryos up to 5 to 6 days, there’s a chance to select more viable embryos, which are more likely competent to result in pregnancy, compared to earlier stages of development. Also, there is a controversy regarding the freeze embryo transfer, compared to the fresh type. Key components that help us to achieve a single embryo transfer (SET) in an IVF-ICSI cycle.
Objectives: To compare the chemical pregnancy rates between fresh embryo transfer (ET), and freeze embryo transfer (FET), on day- 3 (cleavage), and day- 4 (murola) of development.
Materials and Methods: In this retrospective study, data of 242 fresh, and 758 frozen embryo transfer cycles was obtained, in one infertility center in Isfahan, Iran. The study`s groups were assigned based on the day of fresh or freezing embryo transfer (day- 3, or day- 4 embryos), as well as the embryo grading. Chemical pregnancy was the main outcome measurement (Implantation rates).
Results: There were no significant differences, in the demographic characterizations; couples age, duration, cause of infertility, number of transferred embryos, and cause of infertility among different groups. The chemical pregnancy rate was higher in the good quality freeze embryo day- 3 and transfer on day 4 group (40.1%). This rate was highly near to the results of transferring the good quality freeze embryo on day 4 (39.2 %). There was no significant difference in the chemical pregnancy rate, related to the number of transferred embryos (p=0.55).
Conclusion: The higher PRs when the embryos were transferred on day 4, provided further support for the morula stage embryo transfer, which may be because of better synchrony with the endometrium. Also, in the FET cycle, there is no ovarian stimulation. It is concluded that morula/compact embryos are good candidates for embryo transfer, which simultaneously reduces the number of transferred embryos.
Keywords: Ovarian stimulation, ICSI, endometrial receptivity, transfer, synchrony, freeze or fresh embryo.
