#129 : The Ratio of Luteal Phase Serum Progesterone and Estradiol Can be Used to Predict Pregnancy in Frozen Embryo Transfer Cycles

Abstract

Background and Aims: Low serum progesterone (P) levels on day of embryo transfer (ET) and luteal phase have been associated with poorer pregnancy outcome. This study aimed to know if serum estradiol (E2) and P levels during mid and late luteal phase are related with ongoing pregnancy. Method: The serum E2 and P levels from mid luteal phase (5 days after ET) to the day of the [Formula: see text]-hCG check (11 days after ET) in both fresh and frozen embryo transfer (FET) cycles was investigated between January 2019 and December 2021. Eligible patients were reproductive aged women with a normal uterus. Single blastocyst transfer cycles were included. Estradiol valerate (2 mg/bid) was started from day 3 of cycle as hormone replacement and vaginal micronized P (400 mg/bid) was started 5 days before ET in all FET cycles. The 2-degree polynomial fitted data were analysed and logistic linear model and ROC analysis were performed to assess E2 and P4 polynomial coefficients as a predictive test for ongoing pregnancy. Results: A total of 388 patients were included. The overall pregnancy rate was 43.8% and 31.3% for FET and fresh ET, respectively. On day 5 post ET, the serum P levels correlated significantly with ongoing pregnancy and live birth rates, especially in FET cycles. The ROC curve showed that there is a significant day 5 post ET predictive value of serum P4/E2 levels for pregnancy rate, being the AUC (95% CI) = 0.596 (0.539–0.653) for the combination of both fresh and FET cycles; and 0.611 (0.548–0.674) for FET cycles, with best cut-off values of 0.079 and 0.077, respectively. Conclusion: Serum P levels in mid and late luteal phase days are associated with pregnancy outcome both in fresh and frozen ET cycles. Ongoing pregnancies can be predicted using the day 5 post ET serum P4/E2 levels.