Ovulatory cycle frozen embryo transfer yields similar pregnancy outcomes to programmed transfer while avoiding painful injections.

PURPOSE: Optimal endometrial preparation is essential for the transfer of a euploid embryo. Recent works have shown advantages of ovulatory cycle frozen-thawed embryo transfer (Ovu-FET) for simplicity, implantation rate, and reduction of hypertensive disorders of pregnancy; however, few women over age 40 years were included in these studies. This study compared pregnancy outcomes in patients aged 40-45 years between Ovu-FET and programmed cycle FET (PC-FET).

METHODS

Retrospective cohort study in a university-affiliated fertility center. Two hundred eighty-seven FET cycles with euploid embryo transfer between 2015 and 2022 were included, with 116 cycles utilizing the PC-FET and 171 the Ovu-FET protocol. The use of letrozole was permitted for patients with irregular cycles. The primary outcome was ongoing pregnancy rate with secondary outcomes including pregnancy rate, clinical pregnancy rate, biochemical rate, and clinical loss rate. Multivariate regression was utilized to adjust for potential covariates.

RESULTS

The ongoing pregnancy rates were similar between the Ovu-FET versus PC-FET groups (62.6% vs. 58.6%, P = 0.50). Pregnancy rates (77.2% vs. 82.8%, P = 0.25) and clinical pregnancy rates (69.5% vs. 68.1%, P = 0.79) were also similar. Clinical loss rates were similar between the two groups (7.0% vs. 9.5%, P = 0.41). Biochemical loss rates were slightly lower for the Ovu-FET versus PC-FET groups (7.6% vs. 14.7%, P = 0.06) without reaching statistical significance.

CONCLUSION

Our study supports the use of Ovu-FET in women aged 40 years and older undergoing euploid embryo transfers. The results should strengthen confidence in the use of Ovu-FET for older patients.