[The value of serum estradiol concentration on the day of endometrial transformation in predicting the outcome of frozen-thawed embryo transfer in hormone replacement cycle].

To analyze whether the serum concentration of estradiol on the day of progesterone conversion could predict the pregnancy outcome of frozen-thawed embryo transfer in hormone replacement cycle. In this paper, a case-control study was conducted to retrospectively analyze the 230 cycles of hormone replacement therapy-frozen thawed embryo transfer(HRT-FET)conducted by the Department of Reproductive Medicine, Beijing Obstetrics and Gynecology Hospital, Capital Medical University from January 2018 to December 2020. The concentration of serum estradiol was between 139.5-3 941.0 pg/ml. According to the percentile of serum estradiol concentration on the day of endometrial transformation, patients were divided into three groups: control group (<25th percentile, =58), high estradiol group (25th-75th percentile, =112) and ultra-high estradiol group (>75th percentile, =60). Comparing the basic characteristics and pregnancy outcome of the three groups, the main observation index was the live birth rate, and the secondary observation index was the clinical pregnancy rate. test and Kruskal-Wallis () test were used to compare the measurement data, and χ test was used to compare the counting data. The results showed that there was no significant difference in age, anti-Müllerian hormone(AMH), antral follicle count(AFC), body mass index(BMI), years of infertility and the proportion of primary infertility among the three groups(=2.375, =5.479, =5.374, =1.391, =4.779, χ²=1.969, >0.05). FET cycle treatment: There was no significant difference in the concentration of progesterone (P) before transformation, the thickness of endometrium on the day of transformation, the proportion of single embryo transfer and blastocyst transfer among the three groups (=5.359, =5.957, χ²=0.626, χ²=4.532, >0.05). The days of estrogen administration before endometrial transformation in the three groups during the FET cycle were 13.0 (12.0, 14.0) days in the high estradiol group and 13.0 (12.0, 15.0) days in the ultra-high estradiol group, which were significantly longer than those in the control group 13.0(12.0, 13.3)days. The E2 concentration before intimal transformation in high estradiol group was 1 560.4 (1 170.2, 1 848.2) pg/ml, while that in ultra-high estradiol group was 2 420.9 (2 131.0, 2 849.2) pg/ml, which was significantly higher than that in control group 238.8 (206.9, 287.0) pg/ml. The pregnancy outcome of the three groups: the clinical pregnancy rate of the three groups was 37.9% in the control group, 51.8% in the high estradiol group and 40.0% in the ultra-high estradiol group, of which the high estradiol group had the highest clinical pregnancy rate, followed by the ultra-high estradiol group. But there was no significant difference among the three groups (χ²=3.853, >0.05). The embryo implantation rate of the three groups was 19.3%, 25.0%, 32.8%, respectively, and the embryo implantation rate of the ultra-high estradiol group was the highest, but there was no significant difference among the three groups (χ²=5.544,>0.05).The live birth rate of the three groups was 37.9%, 39.3%, 40.0%, respectively, and the difference was not statistically significant (χ²=0.05, >0.05). A total of 14(13.5%) abortions occurred in 104 clinical pregnancies, all of which occurred in the high estradiol level group. Of the 104 clinical pregnancies, 24 (23.1%) had twin pregnancies, which occurred in the high estradiol level group (10 cases) and the ultra-high estradiol level group (14 cases). There were no twin pregnancies in the control group. Ectopic pregnancy occurred in 4 of 230 FET cycles (1.7%), 2 in control group and 2 in high estradiol group, and no ectopic pregnancy in ultra-high estradiol group.