Objective: To observe the effects of serum progesterone concentrations measured on the day before transfer on pregnancy, miscarriage and live birth rates in frozenthawed embryo transfer (DCE) cycles. Materials and Methods: In this retrospective study, the results of 67 ICET cycles performed in a single center between 01.01.2019 and 01.09.2019 were analyzed. Pregnancy, abortion and live birth outcomes were compared in DCE cycles below and above the threshold value of 10.64 ng/ml of progesterone. Results: According to progesterone concentrations, the age, causes of infertility, stimulation days, body mass index (BMI) values, endometrial thicknesse, and mean number of embryos transferred were similar in the groups. When pregnancy rates were compared in terms of progesterone concentrations, pregnancy rates were significantly higher in the progesterone>10.65 ng/ml group p=0.023. We found that 50% (21) of total pregnancies resulted in a live birth, and 90.5% (19) of pregnancies resulting in live birth consisted of pregnant women whose progesterone levels were progesterone>10.64 ng/ml. Those whose progesterone levels were <10.64 ng/ml constituted 28.6% (12) of positive pregnant women, 83.3% (10) of these pregnancies were found to be with miscarriage, and 16.7% (2) of them resulted with live births. Conclusion: It is observed that pregnancy outcomes are higher in cycles where progesterone levels are progesterone>10.64 ng/ml, and most of the pregnancies that occur result in a live birth.