#390 : Why Our Clinical Pregnancy Rates Have Improved Over the Past Two Years: Exploring Key Points of Gonadotropin-Releasing Hormone Antagonist Protocol in Fresh Embryo Transfer Cycles
Authors: Dong Mei , Sun Li 
Published: January 2024

Background and Aims: GnRH-ant protocol is effective in preventing a surge of pituitary luteinising hormone during controlled ovarian stimulation. In recent years, GnRH-ant protocol has been optimised to improve in vitro fertilisation outcomes. However, firstly, the success rate of frozen embryo transfer is consistently better than that of fresh embryo transfer and secondly, the success rate of GnRH-ant protocol on fresh embryo transfer is lower than that of the long protocol. This study aims to draw out a comparison of before and after data from our own centre to find the reasons for the gradual maturation of GnRH-ant protocol on fresh embryo transfer. Our study proposed to investigate the determinants affecting fresh embryo transfer in gonadotropin-releasing hormone antagonist (GnRH-ant) protocols.

Method: We reviewed 2464 fresh embryo transfer cycles for IVF/ICSI-ET assisted reproduction techniques performed at our centre from 1 January 2015 to 31 December 2019. The exclusion criteria were as follows: endometriosis grade III to IV (American Fertility Society classification of endometriosis); adenomyosis; severe male oligospermia or obstructive azoospermia. Firstly, we compared the single-cycle clinical pregnancy rates between 2015 to 2017 and 2018 to 2019. Next, we performed a multifactorial regression analysis to understand what changes our centre had made between the five years in terms of years. Finally, data from 2015 to 2019 were grouped as a whole and then subjected to understand exactly where the differences in clinical pregnancy rates were affecting the GnRH-ant protocol for fresh embryo transfer.

Results: A total of 1,388 cycles were included from 2015 to 2017, with a clinical pregnancy rate of 51.42% (688/1388). 1,076 cycles were included from 2018 to 2019, with a clinical pregnancy rate of 57.43% (618/1076). 2018 to 2019 compared to 2015 to 2017 for first-time IVF/ICSI. There was a 6.01% increase in clinical pregnancy rate for women who had assisted conception and performed GnRH-ant protocol with fresh embryo transfer. The results of the univariate analysis conducted suggested that the factors influencing the classification of clinical pregnancy included female basal E2 base, LH base, FSH base, P base, female Gn initiation date E2 start, LH start, FSH start, P start, Gn initiation volume and number of Gn days, antagonist addition date E2 add, LH add, FSH add, P add, plate machine day E2 trigger, LH trigger, P trigger, plate machine day number of different follicles in the meridian follicles 10-14 mm, follicles 14-16 mm, follicles 16-18 mm, follicles 18mm or more. Multifactorial regression analysis after correction suggested that age, BMI, endometrial thickness on the day of transfer, number of embryos transferred and progesterone level on HCG Day were independent influencing factors for successful pregnancy with antagonist regimen and fresh embryo transfer.

Conclusion: Age, BMI, endometrial thickness on the day of transfer, number of embryos transferred and progesterone levels on HCG Day were independent influences.