Abstract: Objective:To investigate the expression and clinical significance of transmembrane protein-45A(TMEM45A) in placental tissues of preeclampsia (PE), and to observe the effect of hypoxia on the TMEM45A expression in human placental trophoblast HTR-8/SV-NEO.Methods:Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression level of TMEM45A mRNA in placental tissues of PE.Western blotting and immunohistochemical(IHC)staining were used to detect the expression level of TMEM45A protein in placental tissues of PE, and the relationship between the expression level of TMEM45A and the clinical manifestations of PE patients was analyzed.The hypoxia model of HTR-8/SV-NEO cells was constructed to explore the effect of hypoxia on the expression of TMEM45A.The RNA-seq dataset and chip data were collected from the Gene Expression Omnibus(GEO)database.Meta-analysis was used to evaluate the influence of TMEM45A on PE, and ROC curve was drawn to analyze the diagnostic ability of TMEM45A.Results:The expression of TMEM45A mRNA and protein in PE placental tissues were higher than those in normal pregnancy placental tissues (P< 0.05).There were no significant differences in age, weight gain during pregnancy, pregnancy time, delivery time, gestational week, neonatal weight, urinary protein and BUN levels between low expression group and high expression group (all P> 0.05).The expression of TMEM45A significantly increased in HTR-8/SV-NEO hypoxic cells(P< 0.05).Meta-analysis showed that TMEM45A was a risk factor for PETotal SMD=1.23 (0.31-2.14), I²=80.0%, P< 0.001.ROC curve analysis showed that TMEM45A had good diagnostic efficacy (AUC=0.788, CI: 0.718-0.847).Conclusion:TMEM45A is highly expressed in placental tissues of PE and has certain diagnostic value for PE.Hypoxic conditions can lead to an increase in TMEM45A expression in trophoblast cells.