Effect of different levels of serum progesterone on day of frozen ET on clinical outcome

Abstract Background Progesterone (P4) plays a critical role in a natural menstrual cycle. It is an essential hormone to have successful embryo implantation into the endometrium. Objective In the current study, we compared the clinical outcomes of patients with different levels of P4 on embryo transfer day and aimed to determine the optimum threshold for P4 in the luteal phase. Material and methods We performed a prospective cohort study on 100 patients who were referred to the Taleqani Infertility Treatment Institute to undergo frozen embryo transfer (FET). Endometrial preparation was programmed using an estrogen (E2) and progesterone supplement. FET was carried out 3 days after administration of the first dosage of progesterone. We measured serum progesterone levels on embryo transfer day. Clinical pregnancy was the main investigated outcome. We used a parametric receiver operating characteristic curve (ROC) to determine the best-cut points of P4 on embryo transfer day. Results Overall, the average endometrial thickness was 7.9 ± 0.2 mm. We observed no association between endometrial thickness and clinical pregnancy ( P value = 0.719). The mean number of the transferred embryos in all investigated cycles was 1.5 ± 0.5, and 80.0% of the transferred embryos were high quality (high and medium level). The average progesterone level in cycles with clinical pregnancy was 17.2 ± 3.3 ng/mL. It was only 13.4 ± 9.4 in patients without clinical pregnancy. The observed difference was statistically significant ( P value = 0.032). The estimated AUC for the drawn ROC curve was 0.71 indicating a high predictive value. Conclusion The current study demonstrated that high and low serum progesterone (P4) levels on embryo transfer day were associated with reduced clinical outcomes following blastocyst transfer during IVF/ICSI. However, more studies with large sizes are required in this regard.