P-398 Elective Oocyte Cryopreservation – a viable alternative as a means of fertility preservation
Authors: Phua C , McArthur S , Murray A , Bowman M 
Published: June 2023

Abstract

Study question
What are the trends in women accessing elective oocyte cryopreservation (EOC) across a multi-site clinic in Sydney, Australia, thaw rates, utilisation and live birth rates

Summary answer
Over 9 years, there was a significant increase in women having EOC. 2.7% returned to use. Oocyte thaw survival rates were 89.5% with LBR 35.5%.

What is known already
Data from Australia/New Zealand and USA demonstrated a 3 to 8-fold increase in EOC cycles, with a reduction in mean age of women accessing treatment. &lt;5% of women returned to use their frozen gametes and live birth rates were better in women aged &lt; 35 years. HFEA data demonstrated the use of frozen oocytes did not appear to increase risk of adverse perinatal outcomes. Research has shown that almost half of the women who returned to use their frozen oocytes used donor sperm with an overall LBR of 20.9%. 91% of women had no regrets over their decision for EOC.

Study design, size, duration
This was a retrospective cohort study performed at a multi-site large private fertility clinic in Sydney, Australia. This clinic was the first in Sydney to offer EOC to women. All women accessing EOC from 2014 – September 2022 were included. Ethics approval was obtained.

Participants/materials, setting, methods
Data was collected from women undergoing EOC; including demographic information, controlled ovarian stimulation parameters, return to use, oocyte thaw survival rates, source of sperm used for fertilization, embryo biopsy rates, aneuploidy rates, as well as pregnancy rates.

Main results and the role of chance
There was a 17.5-fold increase in cycles of EOC over the 8-year study period; with a reduction in average age from 38.13 to 35.85 years. Overall the mean age was 36.6 of the 2278 women who underwent EOC, of which 30% were aged &gt;38 years. The mean oocyte yield was 8.85.
Of the 62 (2.7%) women who returned to use their frozen oocytes, 54.8% were &lt; 38 years of age. Oocyte thaw survival rates were 89.5%. The majority of women who returned to use their frozen oocytes, used donor sperm for conception. Fertilization rates with intra-cytoplasmic sperm injection (ICSI) was 65.3%; with 8.3% of oocytes degenerating post ICSI. 41.6% of embryos developed into blastocysts with 27.8% utilization rate (good quality blastocyst formation rate).
Overall LBR was 35.5% for all women. Clinical pregnancy rates (CPR) from warmed oocytes were 46.2% from women aged &lt;38 years old and 22.2% from women &gt;38 years old. Of women who returned for a frozen embryo transfer, LBR was 25%; all occurring in women who froze their oocytes prior to age 38.

Limitations, reasons for caution
In parallel to international studies, very few women returned to use their oocytes; results need to be interpreted with care when counselling women considering EOC. Lifestyle factors were unable to be accounted for. Most women have opted to continue storing and not dispose/donate their oocytes at the time of publication.

Wider implications of the findings
EOC proves to be a viable and useful option for fertility preservation. Due to the small proportion of women who return to use their oocytes; and paucity of data; it would be prudent to improve standardisation of data collection and outcome measure reporting.

Trial registration number
Not Applicable