Reproductive outcomes of embryo cryopreservation and transfer at the start-up phase of fertility preservation in Japan.

Purpose: To verify the effectiveness of embryo transfer (ET) using cryopreserved embryo as fertility preservation (FP).

Methods: This study was a questionnaire survey. The total number of embryo cryopreservation (EC) was investigated between 2014 and 2020. And for patients who underwent ET among study period, details of EC, outcome of ET, number of live births, and mortality were investigated.

Results: Of the 150 facilities, 114 responded (76.0%). A total of 1420 EC were performed during the study period; and ET was performed for 417 patients. Breast cancer was the most common primary disease. A total of 199 live births (including prospective) were obtained by ET; 1.7 EC and 2.2 ET were performed per patient, and live birth rate was 21.4% per ET (28.1% on 35-37-year-old patients). The number of EC and ET increased with age. The final birth rate, including pregnancies other than FP, was 51.8%. Ovarian stimulation with aromatase inhibitors was commonly used, although with no effect on live birth rates. Random start stimulation was also common, experienced by 36.3% of breast cancer patients.

Conclusion: Reproductive outcomes of ETs following EC as FP are acceptable. This research project was registered in the University Hospital Medical Information Network (UMIN000043664).