Oocyte vitrification as an efficient option for elective fertility preservation

Cobo, A, Garcia-Velasco, J A, Coello, A, Domingo, J, Pellicer, A, Remohi, J,
Fertil Steril. Mar. 2016 doi: 10.1016/j.fertnstert.2015.11.027


OBJECTIVE: To provide a detailed description of the current oocyte vitrification status as a means of elective fertility preservation (EFP). DESIGN: Retrospective observational multicenter study. SETTING: Private university-affiliated center. PATIENT(S): A total of 1,468 women who underwent EFP because of age or having associated a medical condition other than cancer (January 2007 to April 2015). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Survival and cumulative live birth rate (CLBR) per consumed oocyte. RESULT(S): Mean age was higher with EFP due to age versus having an associated medical reason (37.7 y [95% confidence interval (CI) 36.5-37.9] vs. 35.7 y [95% CI 34.9-36.3]). In total, 137 patients (9.3%) returned to use their oocytes. Overall survival rate was 85.2% (95% CI 83.2-87.2). Live birth rate per patient was higher in women /=36 years old (50% [95% CI 32.7-67.3] vs. 22.9% [95% CI 14.9-30.9]). CLBR was higher and increased faster in younger women. The gain in CLBR was sharp from 5 (15.4%, 95% CI -4.2 to 35.0) to 8 oocytes (40.8%, 95% CI 13.2-68.4), with an 8.4% gain per additional oocyte, in the /=36-year-old group (from 5.1% [95% CI -0.6 to 10.7] to 19.9% [95% CI 8.7-31.1] when 5-8 oocytes were consumed), reaching the plateau with 11 oocytes (CLBR 35.6%). Forty babies were born. CONCLUSION(S): At least 8-10 metaphase II oocytes are necessary to achieve reasonable success. Numbers should be individualized in women >36 years old. We suggest encouraging women who are motivated exclusively by a desire to postpone childbearing because of age, to come at younger ages to increase success possibilities.