High progesterone levels on the day of embryo transfer are associated with a reduced clinical pregnancy rate

Xin WangLili ZhuangLuqing ZhangZhenteng LiuHuishan ZhaoDongmei ZhaoYingqian PengHongchu Bao^*

• Yantai Yuhuangding Hospital, Yantai, China

Context:Low progesterone levels on the day of embryo transfer have an adverse effect on pregnancy outcomes, but the effect of high progesterone levels on pregnancy outcomes is unclear. Objective:In POSEIDON group 1 patients,we investigated how progesterone levels on the day of embryo transfer affect the clinical pregnancy rate.All patients were prepared for transfer using artificial cycles with a combination of vaginal micronized progesterone and oral dydrogesterone. Design, Setting, and Participants:This is a retrospective cohort study, with data from the Reproductive Center of Yantai Yuhuangding Hospital between January 2016 and December 2023.This study enrolled 402 patients who underwent the transfer of one or two embryos on Day 5 or Day 6. Serum progesterone and estradiol levels were measured on the day of embryo transfer (ET). The primary endpoint was the clinical pregnancy rate. Main Outcome Measures:All patients were divided into three groups according to the 10th and 90th percentile serum P values.All the categorical variables were compared with a Pearson Chi-square test or Fisher's exact test among two groups.The Student's t-test was used to compare two sets of continuous variables.One-way analysis of variance compares multiple sets of quantitative data.A multivariate logistic regression analysis was performed with all the potential confounding variables. Results:Serum P levels were divided into three groups according to the critical points of 9.45 ng/ml and 23.32 ng/ml.The clinical pregnancy rate with 9.45≤serum P<23.32ng/ml was higher than others.There was no significant difference in clinical pregnancy rate among the three groups for 46.2% (serum P <9.45 ng/ml),56.7%(9.45≤serum P<23.32ng/ml)and 40% (serum P ≥23.32 ng/ml.)(F=5.04,P=0.08).Adjusted multivariate logistic regression indicated that women with serum P levels of 9.45≤serum P<23.32ng/ml had significantly higher odds of clinical pregnancy compared to other patients (OR: 1.454; 95% CI: 1.032-2.048; P=0.032). Conclusions:We conclude that serum P levels on the day of ET have an optimal range. Deviations from this range are significantly associated with reduced clinical pregnancy rates.