Development of a Model to Estimate the Optimal Number of Oocytes to Attempt to Fertilize During Assisted Reproductive Technology Treatment.

Importance: Surplus cryopreserved embryos pose a challenge for in vitro fertilization patients and clinics; with Roe v. Wade overturned, some states may deem the discarding of surplus embryos illegal, radically changing in vitro fertilization practice. An evidence-based tool would help limit surplus embryo creation.

Objective: To develop a prediction tool for determining how many oocytes should be exposed to sperm to create embryos to conserve the chance of live birth while minimizing surplus embryos.

Design, Setting, And Participants: This diagnostic study used data from member clinics of the Society for Assisted Reproductive Technology Clinical Outcomes Reporting System between 2014 to 2019. A total of 410 719 oocyte retrievals and 460 577 embryo transfer cycles from 311 237 patients aged 18 to 45 years old who initiated their first oocyte stimulation cycle between January 1, 2014, and December 31, 2019, were included. Data were analyzed from February to June 2022.

Exposures: Female patient age, anti-mullerian hormone level, diminished ovarian reserve diagnosis, number of oocytes retrieved, and the state where the clinic is located were included in the final models.

Main Outcomes And Measures: The algorithm was based on 3 models with outcomes: (1) day of transfer; (2) proportion of retrieved oocytes that become usable blastocysts; and (3) number of blastocysts needed for transfer for 1 live birth to occur.

Results: The median (IQR) age at stimulation cycle start was 35 (29-32) years and the median (IQR) number of oocytes retrieved was 10 (6-17). The likelihood of recommending that all oocytes be exposed to sperm increased with age; less than 20.0% of retrievals among patients younger than 32 years and more than 99.0% of retrievals among patients older than 42 years received recommendations that all oocytes be exposed to sperm. Among cycles recommended to expose fewer than all oocytes, the median (IQR) numbers recommended for 1 live birth were 7 oocytes (7-8) for patients aged less than 32 years, 8 (7-8) for patients aged 32 to 34 years, and 9 (9-11) for patients aged 35 to 37 years.

Conclusions And Relevance: In this diagnostic study of in vitro fertilization cycles, a prediction tool was developed to aid clinicians in determining the optimal number of oocytes to expose to sperm, reducing the number of unused embryos created and immediately addressing current patient and clinician concerns.