P-758 Impact of serum estradiol levels prior to progesterone administration in artificial frozen embryo transfer cycles:a retrospective study over 26,000 cycles

Abstract

Abstract Study question To investigate whether serum estradiol (E2) levels prior to progesterone administration in the FET-cycle affect the Clinical pregnancy rate (CPR) and live birth rate (LBR). Summary answer High serum E2 levels prior to progesterone administration in Artificial endometrial preparation are associated with a decreased live birth rate and clinical pregnancy rate . What is known already Although the use of FET has progressively increased, it is still unknown whether a specific endometrial preparation protocol should be favored over another. Owing to their minimal need for clinic visits and a larger scheduling flexibility, artificial cycles for FET are widely used. Additional to the ultrasonographic endometrial thickness check prior to FET, the need for endocrine monitoring in artificial cycles remains unclear. Specifically, the value of proliferative phase serum hormone measurements remains a point of discussion. Study design, size, duration A total of 26,194 artificial FETs performed in a Tertiary-care academic medical centre between 2016 and 2021 were subdivided into 3 groups according to the following late-proliferative serum E2 level percentiles: ≤p33.3 (E2 ≤118 pg/ml; n = 8784), p33.4–p66.6 (E2 from 118.1 to 231.9 pg/ml; n = 8662) and ≥p66.7 (E2 ≥232 pg/ml; n = 8748). Participants/materials, setting, methods A retrospective study over 26,194 cycles,from 2016 to 2021 were included.Univariable and multivariable logistic regression analysis was performed. Main results and the role of chance In 26,194 cycles, there were significant differences in CPR and LBR among the tri-sectional quantiles groups with E2 levels. After stratifying the analysis by age, BMI, infertility diagnosis, type of embryo transferred, number of transferred embryos, infertility factors, method of fertilization, and endometrial thickness on transfer day, there were still significant differences in CPR and LBR among the tri-sectional quantiles group with E2 levels. Multivariate regression analysis showed that female age, thin endometrium, high serum E2 level, tubal factor infertility were risk factors for CPR and LBR, ICSI fertilization, blastocyst transfer, the number of transferred embryos, ovulation disorder infertility and male factor infertility were protective factors for CPR and LBR, BMI was only a risk factor for LBR. Limitations, reasons for caution •Different routes of administration affect serum estrogen levels,and the relationship of serum estrogen levels and endometrial estrogen concentrations is unclear Wider implications of the findings High miscarriage rate following FET has been a point of debate in literature.Future research should definitely focus on the the usefulness of serum E2 evaluation to optimize the success rate. Trial registration number Not applicable