Comparison of pregnancy rates in antagonist cycles after luteal support with GnRH-agonist versus progesterone: prospective randomized study

Purpose: To compare pregnancy rates in GnRH-antagonist cycles triggered with hCG after luteal phase support with intranasal GnRH-agonist as sole luteal phase support versus standard vaginal progesterone preparation. Methods: Prospective randomized controlled study of patients who underwent antagonist-based IVF cycles triggered with hCG at university-affiliated tertiary medical center between 2020 and 2022. Patients meeting the inclusion criteria were randomly assigned to either intranasal GnRH-agonist or vaginal progesterone for luteal phase support. Pregnancy rates were the main outcome compared between the two study groups. Results: A total of 150 patients underwent 164 cycles, 127 cycles of which were included in the study cohort. Of them, 64 (50.4%) and 63 (49.6%) cycles were treated with GnRH-agonist or progesterone, respectively, as sole luteal phase support. A significantly higher pregnancy rate was demonstrated in the GnRH-agonist group compared with the progesterone group. After adjustment of several potential confounders such as age, body mass index, past obstetric history, number of IVF cycles, oocyte retrieved and embryos transferred, GnRH-agonist was still associated with a higher pregnancy rate (odds ratio 3.4, 95% confidence interval 1.4–8.3). Ovarian hyperstimulation syndrome rates were similar between the groups. Conclusions: This prospective study suggests that nasal GnRH-agonist for luteal phase support is associated with higher pregnancy rates compared with standard progesterone support in an antagonist-based protocol triggered with hCG, while maintaining a similar safety profile. Trial registration: Clinicaltrials.gov NCT05484193. Date of registration: August 02 2022. The trial was retrospectively registered.