Retrospective evaluation of the relationship between progesterone level in the blood and pregnancy success before frozen-thawed embryo transfer

Aim:To examine the effect of blood progesterone levels on pregnancy results in HRT-Frozen embriyo transfer (FET) cycles, on the day of transfer, 4-5 hours before transfer Materials and Methods: In this retrospective study, the pregnancy results of 167 patients who were followed up with the diagnosis of infertility and underwent HRT-FET between December 2021 and April 2023 in our clinic were evaluated.The patients were divided into two groups as those with progesterone levels below and above the threshold of 10 ng/ml. In addition, patients with progesterone levels in the range of 10-30 ng/ml and patients above 30 ng/ml were divided into two groups. In these two separate groupings, the groups were compared according to beta HCG positivity in blood, clinical pregnancy, ongoing pregnancy and pregnancy loss rates. Findings: The patients were divided into three groups according to the progesterone threshold: <10 ng/ml (n=31), 10ng/ml ≤ (n=64) ≤ 30ng/ml, >30 ng/ml (n=72) and they were also divided into 2 groups <10 ng/ml(n=31) and ≥10 ng/ml (n=136) and analyzed. Among our patients, unexplained infertility constituted the largest group with 53.3%. Beta HCG positivity in blood of 30.4%, clinical pregnancy rate of 26.3% and ongoing pregnancy rate of 17.3% were obtained from a total of 167 patients. When we divided our patients into groups according to their progesterone levels, 16.1% blood beta HCG positivity and 12.9% clinical pregnancy rates were obtained in 31 patients below 10 ng/ml progesterone level. We see that all pregnancies end in loss and we do not have any ongoing pregnancies. In the group with progesterone levels between 10-30 ng/ml, we see that we have achieved beta HCG positivity in the blood of 34.4%, clinical pregnancy in 29.7%, and ongoing pregnancy in 23.4% in 64 patients. Our pregnancy loss is observed at a rate of 31.8%. In our 72 patients whose progesterone level is above 30 ng/ml, the rate of beta HCG positivity in the blood is 33.3%, the clinical pregnancy rate is 29.2%, and the ongoing pregnancy rate is 19.4%. Our pregnancy loss results in 41.7%. When we compare the groups, progesterone level of 10 ng/ml and above has a significant positive effect on pregnancy results. The p value for beta HCG positivity in the blood and clinical pregnancies is 0.02, and the p value for ongoing pregnancy andpregnancy loss is 0.01. The difference between our results is significant since the P values are significant below 0.05. When we compare the progesterone level between 10-30 ng/ml and the patient group above 30 ng/ml in terms of pregnancy success, P values for beta HCG positivity in blood, clinical pregnancy, ongoing pregnancy and pregnancy loss is 0.9-0.95-0.58-0.49, respectively. There is no significant difference in terms of pregnancy results. In other words, there is no significant change in pregnancy rates and success at progesterone levels above 30 ng/ml. Conclusion:It was observed that pregnancy results were significantly more successful in cycles with progesterone levels < 10ng/ml. When progesterone levels exceeded 30 ng/ml, it was observed that the success level in pregnancy results was similar to the patient group between 10-30 ng/ml, and higher progesterone levels did not increase success. Keywords: Frozen thawed embryo transfer, pregnancy results, progesterone level.