Low Serum LH Levels on hCG Trigger Day are Associated with Reduced Live Birth Rates in GnRH Antagonist Cycles

Objective: To investigate the association between LH levels on hCG trigger day and reproductive outcomes in patients undergoing GnRH antagonist stimulation followed by fresh embryo transfer.Materials and Methods: A retrospective cross-sectional study was conducted at a university-based infertility clinic between January 2015 and December 2022.The study included normoresponder women aged 40 or younger who underwent fresh, non-donor intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF) treatment cycles using a GnRH antagonist protocol.Results: 105 patients were included in this study.Among them, 41 patients achieved live births.Significant differences in age and serum LH levels on the hCG trigger day were observed between patients who achieved live birth and those who did not, but no significant differences in terms of progesterone levels on trigger day, number of oocytes retrieved, embryo quality, or number of mature (MII) oocytes.The ROC analysis identified an LH threshold of 2.7 mUI/ml with optimal sensitivity and specificity.Older women are at higher risk of unsuccessful pregnancy outcomes (Pregnancy: RR=1.1, 95% CI=1.014-1.194,p=0.022;Live Birth: RR=1.082, 95% CI=0.997-1.174,p=0.06).Age-adjusted multivariate regression analysis revealed a 4.7-fold decrease in pregnancy rates (95% CI=1.929-11.44,p=0.001) and 4.1-fold (95% CI=1.730-9.706,p=0.001) in live birth rates among patients with lower LH levels (2.7 mUI/ml).Conclusion: An LH threshold of 2.7 mIU/ml on the hCG trigger day can be used to predict unsuccessful pregnancy outcomes.A freeze-all strategy might be a prudent choice for the normoresponder women with low LH levels on trigger day.