P-472 Oocyte cryopreservation for social reasons in women ≥ 40 years who decline oocyte donation: anticipated outcomes, myth dispelling, and addressing concerns
Authors: Valcarcel A , Guidobono M  L , Tiverón M , Castro A , Zappacosta Villarroel M  P , Lorenzo F , Viglierchio M  I 
Published: July 2024

Abstract

Study question
Is oocyte vitrification a reproductive viable alternative for women aged over 40 who decline oocyte donation? Under what specific conditions?

Summary answer
Oocyte vitrification could be considered as an acceptable alternative in this patient cohort, with patients being adequately informed about the realistic possibilities.

What is known already
In Argentina, legislation on Assisted Reproduction Technologies endorses assisted reproductive treatments employing women’s own oocytes up to the age of forty-four. This legislative framework has resulted in an increased number of such procedures for women over 40 who decline oocyte donation, as well as a rise in those women in this age group who wish to postpone maternity for social reasons. There are scarce published studies presenting reproductive outcomes using vitrified and thawed autologous oocytes in this specific demographic.

Study design, size, duration
This retrospective observational study, conducted between January 2008 and December 2023, involved 299 patients aged 40 and above who underwent 356 cycles of autologous oocyte cryopreservation (1.2 cycles per patient). Statistical analysis utilized the InStat GraphPad statistical package, including one-way ANOVA and two-tailed Student’s t-test as required.

Participants/materials, setting, methods
Eighty-seven patients thawed their oocytes and performed 95 ICSI procedures followed by 75 embryo transfers. The primary outcome was the live birth rate, with secondary outcomes including oocyte survival rate, fertilization rate, implantation rate, clinical pregnancy rate, and miscarriage rate. Vitrification and thawing of oocytes were performed using the Cryotop method.

Main results and the role of chance
Average age: 41.4± 1.8 years. Average vitrified oocytes: 4.5 ± 3.9 [1-24]. 29.1%(87/299) patients thawed their eggs. Average age at thawing:44.0± 2.7 years [41-50]. Average storage time until use was 2.6 ± 1.9 years. 465 oocytes were thawed (4.9 ± 3.0 oocytes per patient). 31.0% used a donor semen sample and 69% used their partne’s semen sample. Survival rate was 87.1%(405/465). Fertilization rate was 74.3% (301/405). Cleavage rate was 98.0 % (295/301). 78.9% (75/95) of ICSI procedures had embryo transfer (1.9 ± 0.6 embryos per patient). Implantation rate was 8.9% (13/146). Clinical pregnancy rate per transfer was 17.3% (13/75). Miscarriage rate was 23.1% (3/13). Miscarriage rate per transfer was 4.0% (3/75). Live birth rate per transfer was 13.3% (10/75), 11.5% (10/87) per patient who thawed their oocytes and 10.5% (10/95) per ICSI procedure performed. Live birth rate per cryopreserved oocyte was 2.1% (10/465) in the general population and 9.1% (10/110) in those women who achieved at least clinical pregnancy. Women who achieved a healthy live birth had a greater number of vitrified oocytes (7.1 ± 3.1) than those who did not achieve pregnancy (4.9 ± 3.0) (p = 0.02).

Limitations, reasons for caution
This retrospective study’s conclusions are pertinent to a well-defined group of patients, specifically women aged over 40 who decline oocyte donation and have undergone oocyte vitrification.

Wider implications of the findings
Despite the absence of an assurance for a live birth through oocyte vitrification in this cohort, offering clear counsel grounded in variables such as the number of retrieved oocytes and age at the moment of cryopreservation allows for informed communication of realistic possibilities for those patients who decline oocyte donation.

Trial registration number
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