Does the decrease in E2 levels between the trigger of ovulation and embryo transfer affect the reproductive outcome in IVF-ICSI cycles?

Objective: This study aimed to evaluate the effect of the rate of decline in serum estradiol (E2) levels between hCG injection and the day of embryo transfer (ET) on the success of assisted reproductive technology (ART) in women with infertility of different etiologies. Materials and Methods: Women 20-45 years of age who underwent a standard GnRH antagonist or long agonist protocol and fresh ET during day 3 of their first ART cycle were included. Group 1 was diagnosed with low ovarian reserve, group 2 comprised high ovarian responders, and group 3 consisted of normal responders. Both groups were divided into four subgroups according to the decrease in E2 levels between the day of hCG injection and the day of ET. Subgroup A patients had a decrease of <20%, subgroup B a decrease of 20-40%, subgroup C a decrease of 41-60%, and subgroup D a decrease >60%. The primary outcome measure was the effect of an E2 decline, based on the measurement of E2 on the day of hCG administration and day of ET, on the implantation rate. The secondary outcome was the change in E2 values in these three groups. Results: The study was conducted on 1.928 women. Of these, 639 were poor responders (group 1), 502 were high responders (group 2), and 787 women had a normal ovarian response (group 3). Patients with a 60% decrease in their E2 levels on the ET day after hCG had a lower live birth rate (LBR) and higher miscarriage rate (MCR), except normoresponders, in whom a similar decline was significant only with respect to MCR. Conclusion: We indicate that high ovarian responders who underwent fresh ET cycles with a 60% decrease in their E2 levels on the ET day after human chorionic gonadotropin had lower LBRs and higher miscarriage. However, in normoresponder women, this decline was only significant in miscarriage.