A higher number of oocytes retrieved is associated with an increase in 2PNs, blastocysts, and cumulative live birth rates

Objective: To investigate the association between the number of oocytes retrieved and fertilized oocytes, blastocysts, cumulative live birth rate, and primary transfer live birth rate.

Design: Retrospective study.

Setting: Retrieval cycles and linked embryo transfers from the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System.

Patient(s): Patients in the United States undergoing autologous IVF cycles from 2014 - 2019 (n=402,411 cycles).

Intervention: None

Main Outcome Measure: Normally fertilized oocytes, blastocysts, cumulative live birth rate, and primary transfer live birth rate.

Results: There was a strong positive linear correlation between oocytes and fertilized oocytes and between oocytes and blastocysts. The cumulative live birth rate increased rapidly with number of oocytes retrieved to approximately 16-20 oocytes, at which point it continued to increase but with diminishing returns. The increasing trend of cumulative live birth rate was observed when stratifying patients by age and by anti-mullerian hormone and after controlling for confounding variables using multivariate logistic regression. The primary transfer live birth rate also increased with number of oocytes to approximately 16-20 oocytes, at which point it plateaued but did not decline.

Conclusion: A higher number of oocytes retrieved improves cumulative live birth rate without impairing primary transfer live birth rate. This suggests that ovarian stimulation strategies should aim to safely maximize the number of oocytes retrieved.