Efficiency of Autologous Egg Cryopreservation: Eight Years’ Experiences and Clinical Outcomes

Oocyte cryopreservation is one of the state-of-art technologies in human reproductive medicine, which brings opportunities for women to preserve their fertility. In the present study, we analyzed the efficiency and outcomes of 8 years’ autologous egg cryopreservation: Frozen oocytes were warmed from 120 cycles and oocyte survival, fertilization, blastocyst development, clinical pregnancy, embryo implantation, live birth rates and birth weights were collected based on the patients’ ages of <35, 35–37 and > 37 years old. The details of oocyte cryopreservation and the efficiency were further analyzed based on different patient categories. During the study period, 849 oocytes from 120 cycles were warmed. Oocyte survival, fertilization, and blastocyst development were not affected by women’s ages at the time of cryopreservation. However, number of patients without blastocyst formation was significantly (P < 0.05) higher in patients >37 years old (31.2%) than that in patients <35 years old (13.1%). Higher live birth rates were observed in patients <35 (51.1%) and 35–37 (46.7%) years old than in patients >37 years old (28.6%) after fresh embryo transfer. Some patients did not have blastocysts mainly due to low fertilization by poor sperm or small number of oocytes warmed. These results indicate that the efficiency of oocyte cryopreservation, evaluated by live birth and embryo implantation rates is affected by women’s age, number of oocytes warmed and sperm quality.