The impact of serum oestradiol concentration prior to progesterone administration on live birth rate in single vitrified-warmed blastocyst transfer cycles

Research question: Can serum oestradiol concentrations on the day of progesterone initiation predict live birth rates in single, autologous vitrified-warmed blastocyst transfers following artificial endometrial preparation? Design: This retrospective study included the first transfers of 468 patients with unexplained or tubal factor infertility who underwent freeze-all cycles using single, top-quality blastocysts after artificial endometrial preparation from January 2015 to January 2018. Patients were stratified into four groups based on serum oestradiol concentration percentiles on the day of progesterone initiation: Group 1 (<25th percentile), Group 2 (25-50th percentile), Group 3 (51-75th percentile) and Group 4 (>75th percentile). The primary outcome was live birth rate. The secondary outcomes were implantation, clinical pregnancy and multiple pregnancy rates. Receiver operating characteristic (ROC) curves were generated to evaluate serum oestradiol concentrations in predicting implantation, clinical pregnancy and live birth. Results: Similar live birth rates of 51.6%, 55.1%, 54.9% and 56.4% for Groups 1, 2, 3 and 4, respectively, were found. The groups also showed similar implantation and clinical pregnancy rates. ROC analysis revealed that serum oestradiol concentrations on the day of progesterone initiation were not predictive for implantation (area under the curve [AUC] 0.490, 95% CI 0.445-0.554), clinical pregnancy (AUC 0.507, 95% CI 0.453-0.561) or live birth (AUC 0.514, 95% CI 0.461-0.566). Conclusions: Serum oestradiol concentration monitoring just prior to progesterone administration does not appear to be predictive for live birth rates in good prognosis patients undergoing single, autologous vitrified-warmed blastocyst transfer after artificial endometrial preparation. Therefore, the current practice of monitoring serum oestradiol concentration is not supported by this study.