This study investigates the predictive power of serum progesterone/estradiol (P/E2) level for estimating the live birth rate in patients who had a serum progesterone (P) rate ≥ 1.5 ng/mL on the human chorionic gonadotropin (hCG) administration day and who received the gonadotropin-releasing hormone (GnRH) antagonist protocol and intracytoplasmic sperm injection (ICSI). This retrospective cohort study included 176 cycles. The P/E2 ratio was lower in patients with a live birth (0.73 ± 0.54) than those without a live birth (1.05 ± 1.38), but the difference was not statistically significant (p = .158). According to the receiver operating characteristic curve analysis of the hCG day P/E2 ratio, the area under the curve was 0.579 (95% confidence interval: 0.478 - 0.680, p = .158) for predicting live birth. In conclusion, this study suggests that a P/E2 ratio is not a significant predictor of a live birth rate in the patients with an hCG-day serum progesterone level of ≥1.5 ng/mL undergoing GnRH antagonist ICSI cycles with a fresh embryo transfer. Impact statement What is already known on this subject? As the progesterone (P) levels in the late follicular phase correlate with the estradiol (E2) levels and the increase in mature follicles, earlier studies have proposed the trigger-day progesterone/estradiol (P/E2) ratio as a potential new marker for a premature luteinisation and live birth success. Most of these studies were conducted on long agonist cycles, and found that arbitrarily defined P/E2 ratio of >1 to be associated with poor pregnancy outcomes. What do the results of this study add? This study retrospectively examines the gonadotropin-releasing hormone (GnRH) antagonist cycles with a trigger-day serum P value of ≥1.5 ng/mL undergoing the intracytoplasmic sperm injection (ICSI) treatment. The receiver operating characteristic (ROC) curve analysis did not identify a statistically significant threshold value for the trigger-day P/E2 ratio that was beneficial in predicting a live birth. The P/E2 ratio was also lower in the cycles with a live birth than those without a live birth, although the difference was not statistically significant. What are the implications of these findings for clinical practice and/or further research? The trigger-day P/E2 ratio does not seem to be an efficient prognostic factor for a live birth in the GnRH antagonist ICSI cycles with a trigger-day serum progesterone level of ≥1.5 ng/mL. Further studies are needed to clarify the association of the trigger-day P/E2 ratio and the pregnancy outcomes in GnRH antagonist ICSI cycles.
Keywords: Intracytoplasmic sperm injection; gonadotropin-releasing hormone antagonist protocol; hCG-day; progesterone; progesterone/estradiol ratio.