Pregnancies and births after oocyte cryopreservation.

Objective: To determine the potential of oocyte cryopreservation techniques.

Design: Retrospective data analysis.

Setting: A tertiary infertility center.

Patient(s): Sixty-eight patients (29 to 37 years of age) undergoing assisted reproduction procedures for infertility problems.

Intervention(s): Oocytes from women treated for infertility were cryopreserved with a slow cooling/rapid thawing protocol in which 1,2 propanediol and sucrose were used as cryoprotectants. Eighty-six thawing cycles were performed.

Main Outcome Measure(s): Rates of survival after thawing, fertilization after intracytoplasmic sperm injection, cleavage, implantation, and pregnancy.

Result(s): We treated 68 patients through 86 thawing cycles. Seven hundred thirty-seven oocytes were thawed, and 59 transfer cycles were performed. The survival rate was 37%. The fertilization and cleavage rates were 45.4% and 86.3%, respectively. A total of 15 clinical pregnancies were achieved with pregnancy rates of 25.4% per transfer and 22% per patient. There were three miscarriages, resulting in an abortion rate of 20%. Seventeen of the 104 transferred embryos implanted, corresponding to an implantation rate of 16.4%. Thirteen babies were born, 8 females and 5 males.

Conclusion(s): Statistically significant results were obtained for fertilization, cleavage, and pregnancy rates. Our results show oocyte cryopreservation may represent an alternative to embryo storage in selected cases.