Agonist Versus Antagonist in Intracytoplasmic Sperm Injection Cycles: Which Is the Best?

Objectives: The comparison of gonadotropin-releasing hormone (GnRH) agonist against GnRH antagonists regarding the pregnancy rate and effect of various predictors on pregnancy outcomes. Materials and Methods: This prospective comparative study involved 189 women who underwent intracytoplasmic sperm injection (ICSI) cycles and were divided into agonist (107 patients) and antagonist arm (82 patients) groups. The chemical and clinical pregnancy rate was the main outcome and the other outcomes included the number and quality of oocyte measurement and pregnancy outcomes. Results: Based on the results, the agonist protocol showed a higher rate of pregnancy (32.7%, 95% CI: 23.9-42.4%) compared to the antagonist protocol (22.0%, 95% confidence interval (CI): 13.6-32.5%) with the odds ratio (OR) of (95% CI) = 1.73 (0.89-3.35). The results further revealed that the count of retrieved oocytes, count of M2 oocytes, count of fertilized oocytes, count of embryos, and the fertilization percent out of total retrieved oocytes were higher in the agonist arm compared to the antagonist arm. In the multivariate analysis after adjusting for the confounders, the agonist protocol had higher odds of a successful pregnancy compared to the antagonist protocol by 57% (partial OR = 1.57, P value = 0.23). Conclusions: In general, the agonist protocol offers a favourable outcome in comparison to the antagonist arm, and there seems to be an intrinsic benefit for the agonist protocol, which is not explained by the higher number of transferred embryos.