The clinical efficacy evaluation of endometrial receptivity analysis (ERA) and Study on the influence factors of displaced window of implantation (WOI): A 6-year retrospective study on a large sample
Authors: Xu Shaoyuan , Diao Honglu , Xiong Yao , Zhang Changjun , Zhang Ying , Zhang Yuanzhen 
Published: May 2024

Background: The endometrium in a receptive status is critical for a successful embryo implantation, but the receptivity of endometrium to embryos is only a short period of time, and the window of implantation (WOI) of each woman has individual variation, which will lead to poor outcomes of assisted reproduction. This so-called window of implantation can be detected by molecular diagnostic method, endometrial receptivity analysis (ERA), which was gradually applied to clinical practice. This study aimed to evaluate the clinical efficacy of personalized embryo transfer (pET) guided by ERA in patients with and without RIF, statistically analyze the clinical factors correlated with displaced WOI.
Methods: A total of 3605 patients with previous failed embryo transfer (ET) cycle in the Reproductive Medicine Center, Renmin Hospital, Hubei University of Medicine from January 2016 to October 2022 were retrospectively analyzed. 3605 patients were divided into non-RIF group and RIF group, among them 782 patients who received ERA test underwent personalized embryo transfer (pET). The decision whether to accept ERA test or not was based on the patient's voluntary choice. We divided the 782 patients into normal WOI group and displaced WOI group according to the result of ERA test. The pregnancy outcomes were compared between the different groups. The age, number of previous ET cycle and serum E2/P ratio were mainly analyzed to investigate its relationship with displaced WOI.
Results:The clinical pregnancy rate and live birth rate in non-RIF with pET group were higher than that of non-RIF with non-personalized embryo transfer (npET) group (64.5% vs 58.3%, P=0.025; 57.1% vs 48.3%, P=0.003). The clinical pregnancy rate and the live birth rate in RIF with pET group were significantly higher than that of RIF with npET group (62.7% vs 49.3%, P<0.001; 52.5% vs 40.4%, P<0.001) after propensity score matching (PSM). The early abortion rate in the non-RIF with pET group was lower than that in the non-RIF with npET group (8.2% vs 13.0%, P=0.038). There was a significant difference in age and the number of previous failed ET cycle between the normal WOI group and displaced WOI group (age:32.26 vs 33.53 years, P<0.001; the number of previous failed ET cycle:1.68 vs 2.04, P< 0.001). Logistic regression analysis also showed that the age and number of previous failed ET cycles were positively correlated with displaced WOI. The displaced WOI rate increased gradually with the increase of age and number of previous failed ET cycle; the displaced WOI rate in the median group 4.46<E2/P≤10.39 pg/ng was significantly lower than that in the other two groups (54.8% vs 40.6% vs 58.5%, P<0.001).
Conclusion:The clinical pregnancy rate and live birth rate of patients with previous failed ET cycle was improved after pET guided by ERA, especially in RIF patients; the early abortion rate of the non-RIF patient was reduced after pET guided by ERA. An appropriate E2/P ratio was beneficial for maintaining endometrial receptivity state, and the age and number of previous failed ET cycle was correlated with increased displaced WOI.