Clinical outcomes and utilization from over a decade of planned oocyte cryopreservation

Abstract

Research question: What is the clinical experience of patients who have undergone planned oocyte cryopreservation and oocyte thawing and warming?

Design: Retrospective observational cohort study. All women who completed planned oocyte cryopreservation at a single large university-affiliated fertility centre between June 2006 and October 2020 were identified, including the subset who returned to use their oocytes. Patients who underwent oocyte cryopreservation for medical reasons were excluded. Baseline demographics, oocyte cryopreservation and thawing-warming cycle parameters, and clinical outcomes, were extracted from the electronic medical record. The primary outcome was cumulative live birth rate (LBR), and secondary outcomes were cumulative clinical pregnancy rate (CPR), and CPR and LBR per transfer. Results were stratified by age at time of cryopreservation (<38 and ≥38 years).

Results: Of 921 patients who underwent planned oocyte cryopreservation, 68 (7.4%) returned to use their oocytes. Forty-six patients (67.6%) completed at least one embryo transfer. The CPR per transfer was 47.5% and LBR was 39.3%. The cumulative LBR per patient who initiated thawing-warming was 32.4%. Cycle outcomes were not significantly different in patients aged younger than 38 years and those aged 38 years or over. No patient aged 40 years or older (n = 6) was successful with their cryopreserved oocytes. Ten patients (14.7%) who were unsuccessful with their cryopreserved oocytes achieved a live birth using donor oocytes, with most (7/10) of these patients aged 38 years and older.

Conclusion: Only a small percentage of patients returned to use their oocytes, and 32% of those were able to achieve a live birth.

Keywords: Cumulative live birth rate; Elective egg freezing; Fertility preservation; Oocyte cryopreservation; Oocyte usage; Oocyte vitrification.