Oocytes vitrification as an efficient option for elective fertility preservation

Capsule:
A discussion of how oocyte vitrification is clinically efficient for elective fertility preservation in the largest series reported to date and how the demand for this option is increasing.

Authors:
Ana Cobo, Ph.D., Juan A. García-Velasco, M.D., Aila Coello, Ph.D., Javier Domingo, M.D., Antonio Pellicer, M.D., José Remohí, M.D.

Volume 105, Issue 3, Pages 755-764

Abstract:

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 ≤35 years old than ≥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 ≤35-year-old group. The increase was slower with 10–15 oocytes, reaching a plateau CLBR of 85.2%. A milder increase (4.9% gain) was observed 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.

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