Genetic factors in endometrium are likely to be involved in the embryo implantation failure (IF), one of the major limiting factors in the success of in vitro fertilization (IVF). In this study, we aimed to identify critical genes from the transcriptional profile for the establishment of the endometrial receptivity which supporting the normal pregnancy. Three GEO datasets, including 12 samples of IF and 12 samples of controls, were used for the meta-analysis. We identified 182 different expression genes (DEGs) by comparing IF with controls and present here the successful clustering according to sample type, not by the origin. The gene ontology (GO) enriched analysis demonstrated the significant downregulation in activation and regulation of inflammatory and immune response in IF patients. Furthermore, network analysis of down-regulated genes identified the significant hub genes containing GADD45A (growth arrest and DNA damage inducible alpha, Degree = 77), GZMB (granzyme B, Degree = 38) and NLRP2 (NLR family pyrin domain containing 2, Degree = 37). The lower expression of NLRP2, related to inflammatory responses with the most degree in the network, was validatied by other GEO data. Besides, it was confirmed that the NLRP2 could act as a predictor for pregnancy after IVF (AUC = 87.93%; sensitivity, 60.00%; specificity, 91.30% ). Our meta-analysis will help us to better understand the molecular regulation of endometrial receptivity, and guiding further line of treatment for IF during IVF.

Background Previous studies have suggested that pregnancy outcome and endometrial thickness before embryo transfer are closely related. However, we found that endometrial thickness changed even within a few days between HCG day and embryo transfer day. There have been few studies on the relationship between endometrial thickness change (ETC) and pregnancy outcomes. The aim of this study was to assess whether the ETC from HCG trigger day to embryo transfer day affects pregnancy outcomes of in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles. Methods This was a retrospective single-center cohort study. In total, 9773 IVF/ICSI embryo transfer cycles involving the long protocol at Chongqing Reproductive and Genetics Institute from January 1st, 2016, to December 30th, 2019, were included. The 9773 cycles were divided into 2 groups based on whether the endometrial thickness decreased from HCG day to embryo transfer day, and clinical pregnancy rates (CPRs) and ongoing pregnancy rates (OPRs) were compared. Logistic regression was used to determine whether an ETC was an independent risk factor for CPR or OPR. Results The CPR and OPR of the decreased endometrial thickness group were higher than those of the non-decreased endometrial thickness group (62.65% and 52.6% vs. 60.56% and 50.18%) (p = 0.041 vs. 0.027). The endometrial thickness change was an independent risk factor for CPR (OR = 0.920, P = 0.003, 95% confidence interval 0.870–0.972) and OPR (OR = 0.907, P = 0.000, 95% confidence interval 0.859–0.958) Conclusions A proper decrease in endometrial thickness from HCG trigger day to embryo transfer day in IVF/ICSI cycles increases the CPR and OPR.