Outcomes of oocyte cryopreservation: an analysis based on age and treatment indications.

Study Question: How do age at oocyte cryopreservation (OC) and treatment indication affect the outcomes of OC cycles, particularly cumulative live birth rates (CLBR) per warm cycle?

Summary Answer: Age at OC significantly influenced CLBRs per warm cycle, with younger patients achieving higher success, while differences between treatment indications were not statistically significant.

What Is Known Already: OC is a well-established fertility preservation method, with success rates largely influenced by the woman's age at the time of freezing. However, limited data exist on how various medical and non-medical (elective) indications affect outcomes.

Study Design, Size, Duration: This retrospective cohort study analyzed 4577 OC cycles from 3164 women treated between January 2014 and December 2023 at Melbourne IVF clinic, Australia. The primary outcome was CLBR per warm cycle. Secondary outcomes included the number of oocytes cryopreserved, oocyte survival rate upon warming, fertilization rate, good-quality embryo development, clinical pregnancy rate and miscarriage rate.

Participants/materials, Setting, Methods: Data were obtained from electronic clinical records. OC cycles were categorized by age at oocyte retrieval and treatment indication: cancer diagnosis, other medical conditions and non-medical reasons.

Main Results And The Role Of Chance: The mean age at OC was lowest in the cancer group (31.3 ± 6.2 years) compared to other medical (34.4 ± 4.5 years) and non-medical (36.2 ± 3.1 years) groups (P < 0.01). During the study period, 647 warmed oocyte cycles were conducted. Oocyte survival rate was lower in the cancer group (81.5%) compared with other medical (85.3%) and non-medical (83.3%) groups (P < 0.01). The CLBR per started warm cycle was highest in patients under 35 years old (49.0%), followed by those aged 35-40 (36.8%) and lowest in patients over 40 (17.2%) (P < 0.01). Although CLBR appeared lower in the cancer group (35.6%) compared with other medical (36.0%) and non-medical (39.3%) groups, the differences did not reach statistical significance (P > 0.05).

Limitations, Reasons For Caution: The study's retrospective design and the heterogeneity of medical indications in the "other medical" group are notable limitations.

Wider Implications Of The Findings: These findings reinforce the importance of early OC, when age is a controllable factor, to maximize fertility preservation outcomes. While cancer patients showed slightly lower success rates, OC remains a valuable option for these individuals. Further studies are needed to explore the impact of specific cancer types and treatment regimens on oocyte quality and reproductive outcomes.

Study Funding/competing Interest(s): No external funding was received for this study. The authors declare no conflicts of interest.

Trial Registration Number: Not applicable.