Frozen-Thawed Embryos Generated from a Successful Fresh IVF Cycles have Higher Potential for Favorable Outcome than Frozen-Thawed Embryos Obtained from Unsuccessful Fresh Cycles

Introduction: Many variables influence the success rate of either fresh embryo transfer (ET) or frozen-thawed ET (FT-ET) cycles. Patients frequently ask whether previous successful fresh IVF attempt is a positive prognostic factor for their FT-ET.

Aim: To assess whether patients who conceived in a fresh cycle and consequently used their spare frozen embryos generated from the same ovum pickup experienced a better outcome than patients who did not conceive in their fresh cycle.

Materials and Methods: A retrospective cohort study evaluating records of patients that underwent fresh IVF-ET cycle and had at least one consecutive FT-ET using embryos that were obtained from that fresh cycle between 2005- 2015. Comparison of FT-ET cycles details and its outcome was assessed in relation to the outcome of the preceding fresh ET cycles.

Results: A total of 2218 patients with fresh ET and at least one consecutive FT-ET cycle were included. No difference was found in the number of retrieved oocytes, fertilization rates and embryo quality between successful and failed fresh cycles. When consecutive frozen cycles were compared between patients with successful and unsuccessful fresh ET cycles, a significant higher pregnancy rates were observed (26.6% vs. 21.8%; p=0.03). This was substantiated by the McNemar test which showed a significant association between successful fresh cycle and positive outcome in the consecutive FT-ET cycle (P<0.001).

Conclusions: Frozen-thawed embryos generated from a successful fresh IVF cycles have higher potential to implant and result in live birth rates when compared to frozen-thawed embryos obtained from unsuccessful fresh cycles.