P-402 What is the efficacy of planned oocyte cryopreservation? A systematic review and meta-regression analysis
Authors: Hirsch A , Hirsh Raccah B , Rotem R , Hyman J , Ben-Ami I , Tsafrir A 
Published: June 2023

Abstract

Study question
What are the chances of achieving a live birth after planned oocyte cryopreservation (POC)?

Summary answer
The mean thawing rate is 11.9% (± 4.9). Among women who thawed their oocytes, the mean live birth per patient is 28.1% (± 13.0).

What is known already
Trends of delayed childbearing have become increasingly common. The age-related decline in fertility potential increased the popularity of planned oocyte cryopreservation. However, Data on the outcomes of planned oocyte cryopreservation including a return for a thaw, pregnancy, and live-birth rates are scarce, being based mostly on small case series.

Study design, size, duration
A systematic review and meta-regression followed the PRISMA and MOOSE guidelines. A systematic search was conducted in Medline, Embase, and the Cochrane Library. The search strategies incorporated index terms (Mesh) and free text words for the search concepts. The first domain contained terms on indication the second domain related to oocytes cryopreservation. The detailed protocol is documented online in the International Prospective Register of Systematic Reviews registry.

Participants/materials, setting, methods
POC was defined as cryopreservation for future age-related fertility loss exclusively. All studies that reported primary data on POC were considered eligible for screening. Observational and non-observational studies were included. The primary outcome was the live birth rate per woman. The secondary outcomes included the thawing rate and other laboratory outcomes. Meta-regression analyses regarding the association between oocyte survival after thawing and live birth and age above 40 or method of freezing were conducted.

Main results and the role of chance
A systematic search from inception to October 2022 yielded 3847 citations. After the selection process, 9 studies, conducted from 1999 to 2020, were included. In total, 8059 women underwent POC, and 1463 returned to use their oocytes. The mean thawing rate was 11.9% (±4.9). The mean age at thawing was 41.9 years (±0.8) with a mean time from freezing to thawing of 4.0 years (±- 0.4). 68.3% (± 18.4 ) of patients returned with a partner while the others used donor sperm. Five studies used vitrification exclusively while the others included both slow-freezing and vitrification. The oocytes survival rate after thawing was 79.0% (±5.4 ) and the mean live birth per patient was 28.1% (± 13.0). A meta-regression analysis revealed an association between age above 40 years and decreased live birth (R2=0.08) and oocyte survival (R2=0.16). No statistically significant association was found between the method of cryopreservation to oocyte survival rate or live-birth

Limitations, reasons for caution
Variations in expertise and technical experience between different centers may yield different results. In addition, most data reports outcomes for women who underwent POC aged 35-40, while information on women who had this procedure at younger or older ages is scarce.

Wider implications of the findings
Data presented here may be valuable for consultation and informed decision-making of women considering POC

Trial registration number
CRD42022361791 02/10/2022