Clinical pregnancy (CP) and live birth (LB) increase significantly with each additional fertilized oocyte up to nine, and CP and LB decline after that: an analysis of 15,803 first fresh in vitro fertilization cycles from the Society for Assisted Reproductive Technology registry

Abstract

Objective: To study the association between the total number of fertilized oocytes available and pregnancy outcomes in first fresh IVF cycles with a single blastocyst transfer.

Design: Retrospective cohort study.

Setting: Not applicable.

Patient(s): A total of 15,803 patients from SART reporting fertility clinics.

Intervention(s): None.

Main outcome measure(s): Primary outcomes were clinical pregnancy (CP), live birth (LB), and miscarriage rates. Logistic regression was used to investigate the association between the number of fertilized eggs and each outcome.

Result(s): The median number of total oocytes was 15, and the median number of fertilized oocytes was nine. The odds of a clinical pregnancy were 8% higher for each additional fertilized oocyte up to nine (odds ratio [OR] 1.08; 95% confidence interval [CI] 1.07-1.10) and declined by 9% for every additional fertilized oocyte after nine (OR 0.91; 95% CI 0.89-0.94). Similarly, the odds of an LB was 8% higher for every additional fertilized oocyte up to none (OR 1.08; 95% CI 1.06-1.10) and declined by 8% for every additional fertilized oocyte over nine (OR 0.92; 95% CI 0.90-0.94).

Conclusion(s): Odds of pregnancy outcomes (CP, LB) increase significantly with every additional fertilized oocyte up to nine, and CP and LB decline after that in first fresh autologous cycles with a single blastocyst transfer.

Keywords: Clinical pregnancy; IVF; fertilized oocyte; live birth.