Thin Endometrium and Cleavage Embryo Transfer Are Associated With Ectopic Pregnancy After in Vitro Fertilization‑embryo Transfer Cycles: a Matched Case–control Study Using Propensity Score Matching

Abstract

Objective: To evaluate the relationship between the endometrial features (endometrial thickness(EMT), pattern and endometrium growth amplitude and rate) and the embryo stage transferred and ectopic pregnancy after IVF-ET based on the data of 628 matched cases. Methods: This was a 1:1 matched case-control study that enrolled 314 EP patients and 314 matched IUP patients from the ART center of Xiangya Hospital of Central South University from January 2014 to April 2020. Univariate analysis and multiple-stepwise logistic regression analysis was used to analyze the risk factors of EP, and a receiver-operating characteristic (ROC) curve was generated to predict EP. Results: 1. The EP group had a higher cleavage stage embryo transfer rate(94.57% vs 86.22%), a thinner endometrium on transformation day(the day when progesterone was added in the frozen embryo cycle or the trigger day in the fresh embryo cycle) (9.40(2.60) mm vs 9.80(2.60)mm) compared with IUP group. In fresh embryo cycles, the EP group had a higher endometrium pattern C proportion on transformation day, a smaller endometrium increment, and a slower endometrial growth rate compared with the IUP group. 2.The ROC curves were used to analyze the cut-off values of the EMT on transformation day, the endometrial growth amplitude and rate in fresh cycles, the results were 9.35mm, 4.90mm and 0.491 mm/d, respectively. The incidence of EP was significantly different between groups according to cut-off values. 3.The transferred embryo stage and EMT on transformation day were independent factors affecting outcome in the general population. The area under the curve(AUC) of the EMT and the stage of embryos transferred for EP prediction was 0.604, sensitivity was 0.702, and specificity was 0.465. The EMT on trigger day was an independent factor affecting outcome in the fresh cycles. The AUC of the EMT for EP prediction in fresh cycles was 0.605, sensitivity was 0.805, and specificity was 0.420. Conclusions: 1. Transferring cleavage stage embryo, and thin EMT on the transformation day were risk factors for EP. 2. Thin EMT and pattern C on transformation day may be related to abnormal endometrial receptivity and endometrial peristaltic waves. 3.The combined indicator of EMT and embryonic development stage could not well predict the occurrence of EP after ET.