In freeze-all embryo cycles due to endometrial fluid (EF), live birth rates are comparable to those of controls, despite high rates of EF recurrence and cycle cancellation.

RESEARCH QUESTION Do cumulative live birth rates (CLBRs) differ between women who have had a freeze-all embryo cycle (FAE) for endometrial fluid (EF) and controls? DESIGN This retrospective cohort study included 83 women who had a FAE cycle due to the presence of EF between 2010 and 2016 at a university-affiliated private IVF center. The controls were 219 women who had FAE for other indications during the same period and were randomly selected. The main outcome measures were CLBRs, EF recurrence, cancellation and pregnancy loss rates. RESULTS Population characteristics were comparable between the two groups. The CLBR was not significantly different between the EF and the control group: 39.8% vs. 47.0%, respectively, p = 0.26. Cancellation rates in the two first FETs were higher in the EF group than the control group: 18.1% vs. 4.1% (p < 0.001) and 22.9% vs. 8.5% (p = 0.02). After FAE for EF, we observed a significant risk of EF recurrence (32/177 cycles, 18.1%), allowing us to identify a poor prognosis subgroup. When EF was detected, the LBR per transfer was 7.1% (1/14) when the transfer was finally performed (after EF aspiration or EF disappearance), compared to 25% (32/128) in cycles without EF recurrence (p < 0.05). Conversely, in the absence of EF recurrence (145/177, 81.9%), the LBR was comparable to that of the control group. The type of endometrial preparation does not seem to be associated with EF recurrence. CONCLUSION Despite higher rates of EF recurrence and cycle cancellation, women with FAE for EF ultimately have comparable LBRs to those who have had a FAE for other indications. However, women presenting with at least one EF recurrence during FETs seem to have a lower LBR.