P-528 Intra-individual variability of serum progesterone level on the day of frozen blastocyst transfers in hormonal replacement therapy cycles

Abstract Study question Is there a significant intra-individual variability of serum progesterone level on the day theHormone Replacement Therapy Frozen Embryo Transfer(HRT-FET) between two consecutive cycles? Summary answer No measured transfer was shown HRT-FET cycles. What is known already In frozen embryo under HRT, minimum P around transfers necessary to optimize reproductive outcomes. Indeed, in previous study, we have found that women with ≤9.8ng/ml single autologous blastocyst had lower live birth rate. Moreover, some clinical factors been described as influencing (i.e weight, gravidity, Ethnic origin,tobacco consumption…). Variations patients raise variation measurement, addition existence inter-individual variation. design, size, duration We conducted an observational cohort study at university-based medicine centre our institution focusing who underwent least blastocyst, January 2019 and March 2020. Participants/materials, setting, methods Patients undergoing using exogenous estradiol vaginal micronized for endometrial preparation were included.The morning FET, laboratory. The measurements performed first (FET1) second FET (FET2) compared evaluate P.Paired statistical analyses performed, appropriate. Main results role chance Two hundred sixty-four included. mean age included 35.0 ±4.2 years old. observed 1 FET2 (Mean after FET1: 13.4±5.1ng/ml versus 2: 13.9±5.0; p = 0.08).Characteristics similar FET. Forty-nine (18.6%) discordant levels (defined one measurement > ≤ threshold 9.8ng/ml) FET1 FET2. 37/264(14%) high difference values >75 e percentile (6.0ng/ml)) specific parameter associated nor measurements. Limitations, reasons caution This limited by its retrospective design. Likewise, only Wider implications findings showed seems be reproducible more than 80% case. suggests could used individualize luteal phase support subsequent Trial registration number not applicable