Objective: To explore the changes of serum, umbilical vein, placental irisin level, and the correlation between irisin level and relevant indicators in pregnant women with intrahepatic cholestasis of pregnancy (ICP), so as to provide a new perspective for in-depth studies on the causes and treatment of ICP.Methods: This cross-sectional case-control study method, the serum, umbilical venous blood irisin, liver, kidney function, lipid metabolism, and other indicators of 108 normal pregnant women, 64 patients with mild ICP, and 39 patients with severe ICP were compared, and the changes in the levels of oxidative stress and irisin were observed by dihydroethidium staining and immunohistochemistry.Results: The level of placental oxidative stress in severe ICP group and mild ICP group was significantly higher than that in normal pregnant women group, and the mild ICP group was significantly higher than that in severe ICP group (p < .05); the concentration of irisin in umbilical vein was significantly lower than that in peripheral blood; the serum irisin of normal pregnant women (918.51 ± 159.90 pg/ml) was significantly lower than that of pregnant women with mild ICP (1030.05 ± 137.98 pg/ml) and pregnant women with severe ICP (1094.34 ± 154.35 pg/ml). The concentration of irisin in umbilical vein blood of pregnant women with severe ICP (858.78 ± 97.42 pg/ml) was significantly higher than that of normal pregnant women (595.33 ± 162.70 pg/ml) and those with mild ICP (648.82 ± 164.81 pg/ml) (p < .05). Irisin was expressed in placental tissues of normal pregnant women group, mild ICP group and severe ICP group, and the differences were statistically significant in expression intensity of the three groups (χ2 = 19.959, p < .05). The irisin expression intensity in the ICP group was higher than that in the control group, and the irisin expression intensity in the ICP group was higher than that in the ICP group (β = 0.292; t = 3.063; p < .05). At the best cutoff level of 989.168 pg/ml, irisin accurately predicted ICP [AUC = 0.622 (95%CI 0.543-0.701, p < .05)] with sensitivity and specificity rates of 60.9 and 40.1%, respectively.Conclusion: Irisin can reduce the level of oxidative stress and improve lipid metabolism in ICP patients during the pathophysiological process of ICP, and it is possible to become a new auxiliary factor of ICP diagnosis and indexing. [ABSTRACT FROM AUTHOR]