Background: It was thought that using oral contraceptives or GnRH agonists as a pre-treatment for synchronization of multi-follicular growth and enhancement of COH outcomes offers a higher physiological possibility.
Objective: Investigate whether pretreatment with E2 during the luteal stage influences the growing follicles' development.
Methods: A randomized controlled trial was performed. 114 infertile couples undergoing intracytoplasmic sperm injection—embryo transfer were included and divided equally into two groups. Group 1: 57 women received estradiol (E2) pretreatment and then underwent an ICSI cycle, Group 2: 57 women who directly underwent ICSI without pretreatment. The ovarian response was evaluated, and A fixed antagonist protocol was employed in both groups. Day 3 ET of good quality embryos were applied.
Results: Group 2 was significantly higher on stimulation days, daily dose of hMG, and gonadotropin ampoules than in Group 1. Number of follicles on day of hCG in group 1 was 9.81± 5.42 and in group 2 was 10.60± 6.54 (P=0.803), also no difference was observed in the number of mature oocytes or the number of high-quality embryos between the two groups. The clinical pregnancy rate was insignificantly increased, in patients received E2, 66.7% vs. 54.4%, in group 1 and group 2, respectively (P = 0.180). The implantation rate increased significantly in group 1 than in group 2 (49.70±41.99% vs. 35.93±39.85%, respectively; P = 0.045).
Conclusion: Estradiol pretreatment in antagonist cycles improves the positive pregnancy rate and implantation rate with a tendency to require lower hMG doses and a shorter stimulation duration.