Total blastocyst usable rate is a predictor of cumulative live birth rate in IVF cycles

Despite advances in IVF techniques, determining the prognostic factors influencing cumulative live birth rate (CLBR) remains crucial for optimizing outcomes. Among the various key performance indicators in the lab, blastulation rate, and more specifically Total Blastocyst Usable Rate (TBUR), has gained particular interest. In this study we aimed at determining if TBUR was significantly associated with CLBR.

This monocentric retrospective case-control study was conducted in 317 consecutive IVF/ICSI cycles in 2014-2020 and leading to the formation of 3 usable blastocysts, including freeze all cycles. TBUR (usable blastocysts / 2PNs) was calculated and CLBR after 2-year follow up was recorded, including both fresh and frozen embyro transfers. CLBR was then compared between 2 groups according to TBUR (group 1: TBUR ≥50 % vs group 2: TBUR ≤30 %).

CLBR was significantly higher in group 1 than in group 2 (57 vs. 41 %, p = 0.02). Adjusted logistic regression showed a statistically significant relationship between CLBR and TBUR, with a significantly lower chance of achieving a live birth in group 2 than in group 1 (OR = 0.408 [0.17-0.96]; p = 0.04).

Although the monocentric design and the arbitrary choice of thresholds for TBUR and number of blastocysts call for caution when generalizing the findings and advocates for external validation, our results illustrate that TBUR is a valuable prognostic factor of CLBR in IVF cycles which might serve as a tool for lab monitoring, cycle analysis by medical staff and patients' counselling. These results fit well within the P4 medicine concept (Predictive, Preventive, Personalized, and Participatory), and advocate for further research in order to improve embryo culture conditions.