Frozen-thawed embryos generated from successful fresh IVF cycles have higher potential for favorable outcome than frozen-thawed embryos obtained from unsuccessful fresh cycles: A retrospective cohort

Abstract Background: Many variables, including woman`s age, embryo quality and endometrial receptivity, influence the success rate of either fresh embryo transfer (ET) or frozen-thawed ET (FT-ET) cycles. The aim of this study is to examine whether the results of a fresh in-vitro fertilization (IVF) cycle correlates with its frozen-thawed embryos transfer outcomes. Methods: A retrospective cohort study conducted in a tertiary medical center single IVF unit between 2014 and 2017. The study population was comprised of women who underwent fresh ET with the remaining embryos frozen using vitrification and at least one consecutive FT-ET cycle. Comparison of FT-ET cycle's details and outcomes were assessed in relation to the outcome of the preceding fresh ET cycle . Results: A total of 599 women underwent fresh ET and at least one consecutive FT-ET cycle. Significantly higher rates of successful FT-ET cycle outcomes were observed in the group of patients with a successful fresh cycle compared to the group with an unsuccessful fresh cycle (48.9% vs. 20.8%, p<0.001). Logistic regression demonstrated an adjusted OR of 5.02 for successful FT-ET after a successful fresh cycle. Conclusions: Frozen-thawed embryos generated from successful fresh IVF cycles have higher potential to implant when compared to frozen-thawed embryos obtained in an unsuccessful fresh cycles.