Association Between Progesterone Level on Trigger Day to Basal Progesterone Ratio and in vitro Fertilization-Embryo Transfer Outcomes in Antagonist Protocols

Miao-Yi Xu, Yu-Ting Wang, Yao-Fang Liu Department of Reproductive Technology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, 646000, People’s Republic of ChinaCorrespondence: Yao-Fang Liu, Department of Reproductive Technology, The Affiliated Hospital of Southwest Medical University, No. 25 of Taiping Street, Luzhou, Sichuan Province, 646000, People’s Republic of China, Tel +860830-3165649, Email [email protected]: To investigate the relationship between the progesterone level on trigger day (Ptrigger) to basal progesterone (bP) ratio and the outcomes of in vitro fertilization-embryo transfer (IVF-ET).Methods: A retrospective analysis was conducted on women who received an antagonist protocol, with a Ptrigger less than 1.5 ng/mL and who underwent fresh embryo transfer. Based on the Ptrigger/bP ratio, participants were categorized into four groups: group A (Ptrigger/bP < 1, n = 284), group B (Ptrigger/bP ≥ 1 and < 2, n = 363), group C (Ptrigger/bP ≥ 2 and < 3, n = 165), and group D (Ptrigger/bP ≥ 3, n = 118). Recombinant follicle-stimulating hormone was used to stimulate ovulation. Receiver operating characteristic curve analysis was used to analyze the accuracy of the Ptrigger/bP ratio in predicting clinical pregnancy following fresh embryo transfer.Results: A decreasing trend in bP levels was observed across groups (A > B > C > D), while Ptrigger levels showed an increasing trend (A < B < C < D). Groups A and B included significantly younger women and required lower doses of gonadotropin (Gn) compared to Groups C and D. The embryo implantation and clinical pregnancy rates in Group A were 34.93% and 49.30%, respectively, significantly higher than those in Group D (23.19% and 33.90%, respectively). After propensity score matching for age, the differences in implantation and clinical pregnancy rates were not statistically significant between Group A and D. The Ptrigger/bP ratio had limited accuracy in predicting clinical pregnancy, with an area under the curve of 0.538 (95% CI [confidence interval]: 0.501– 0.575, P = 0.044).Conclusion: A Ptrigger/bP ratio of less than 1 was associated with relatively favorable pregnancy outcomes in women undergoing IVF-ET with an antagonist protocol for ovulation induction.Keywords: antagonist protocol, basal progesterone, bP, IVF-ET outcome, in vitro fertilization-embryo transfer, IVF-ET, progesterone level on trigger day, Ptrigger