Effect of Triggering with hCG Alone, GnRH Agonist Alone, or in Combination (Dual Trigger) in Letrozole-Stimulated Cycles for Frozen-Thawed Embryo Transfer: A Retrospective Cohort Study

Abstract

Abstract Objective The objective of this study was to evaluate the effects of triggering strategies on pregnancy outcomes in letrozole-stimulated cycles for frozen-thawed embryo transfer (L-FET), employing the gonadotropin-releasing hormone agonist (GnRHa) and human chorionic gonadotropin (hCG) combination, the conventional hCG trigger alone and the GnRHa trigger alone. Materials and Methods 773 women undergoing L-FET were enrolled in this retrospective study. The grouping of the participants was based on the trigger method employed. The dual trigger group (N = 105) was given 0.1 mg GnRHa and 2000 IU hCG, the hCG trigger group (N = 430) was administered 4000–10000 IU hCG, and the GnRHa trigger group (N = 238) was injected with 0.1 mg GnRHa alone. Binary logistic regression analysis was conducted to evaluate the influence of potential confounding factors on pregnancy outcomes. Additionally, subgroup analysis was performed in accordance with the hCG trigger dose. Results A lower miscarriage rate was observed in GnRHa trigger group (adjusted odds ratio (aOR) = 0.484, 95% CI 0.244–0.962, P = 0.038) and hCG trigger group (aOR = 0.395, 95% CI 0.196–0.798, P = 0.010) compared with dual trigger group. The positive pregnancy rate, clinical pregnancy rate and ectopic pregnancy rate were slightly higher in dual trigger group, nevertheless, the differences were not statistically significant (P values were 0.764, 0.892 and 0.705 respectively). The live birth rate was slightly higher in hCG trigger group (40.2%) compared to the GnRHa trigger group (38.2%) and dual trigger group (34.3%), but the difference was not significant (P = 0.521). In the subgroup analysis, no significant difference was found on pregnancy outcomes among different hCG trigger dose groups (P > 0.05). Conclusion Dual trigger could increase miscarriage rate in women undergoing L-FET. Hence, the routine use of dual trigger for ovulation induction is not recommended in L-FET. Moreover, luteal support should be given flexibly and cautiously whenever employed. Noteworthily, these findings indicate that the 4000 IU hCG trigger could be a potentially better alternative for patients undergoing L-FET, particularly when considering cost-effectiveness.