Developing a decision support tool to optimize oocyte thawing for producing at least three euploid blastocysts

Area of Science:

• Reproductive endocrinology and infertility
• Assisted reproductive technologies
• Oocyte cryopreservation and thawing outcomes

Background:

• Optimizing the number of oocytes thawed is crucial for maximizing the yield of euploid blastocysts in fertility treatments.
• Previous studies have not definitively established the ideal number of oocytes to thaw to achieve a target of at least three euploid blastocysts.

Purpose of the Study:

• To determine the optimal number of oocytes that need to be thawed to achieve a minimum of three euploid blastocysts.
• To analyze the impact of oocyte thaw quantity on laboratory outcomes and success rates across different age groups.

Main Methods:

• Retrospective cohort study analyzing 417 oocyte thaw cycles from 2012-2024 at a single fertility clinic.
• Patients were stratified into groups based on the number of oocytes thawed (2-8, 9-11, 12-16, >16).
• Exclusion criteria included lack of preimplantation genetic testing for aneuploidy, combined thaw cycles, or fresh embryo transfers.

Main Results:

• Thawing >16 oocytes (Group D) resulted in 50.0% of patients achieving ≥3 euploid blastocysts, compared to 27.7% in Group C (12-16 oocytes).
• For patients <38 years, thawing 12-16 oocytes yielded similar odds of ≥3 euploid blastocysts as thawing >16 oocytes.
• Patients aged ≥38 years had a significantly lower success rate, with only 3.4% achieving ≥3 euploid blastocysts.

Conclusions:

• Thawing 12-16 oocytes is sufficient for patients under 38 to achieve ≥3 euploid blastocysts, comparable to thawing more.
• Patients with fewer than 12 vitrified oocytes should thaw all available oocytes or consider additional cryopreservation.
• For patients with ample oocytes, limiting the thaw to 16 may be reasonable, as thawing more does not appear to increase live birth chances.