Objective To explore the correlation of body mass index,urinary protein and tumor necrosis factor-like weak inducer of apoptosis(sTWEAK)during pregnancy with the severity of preeclampsia and pregnancy outcome.Methods A total of 63 patients with preeclampsia who were examined in Xingtai People's Hospital from April 2022 to April 2023 were enrolled in the study,33 patients with mild preeclampsia were included in the mild group and 30 patients with severe preeclampsia were included in the severe group.Physi-cal characteristics,urinary protein and sTWEAK levels between the groups were recorded,and the patients were followed up to explore the correlation with pregnancy outcome.Results The systolic and diastolic blood pressure of patients in the mild group were lower than those in the severe group,and the plasma albumin was higher than that in the severe group(P＜0.05).There was no statistically significant difference in pre preg-nancy weight and pre pregnancy body mass index between the mild and severe groups of patients(P＞0.05).The delivery weight and weight gain during pregnancy in the mild group were lower than those in the severe group(P＜0.05).The 24-hour urinary protein quantification in the mild group was lower than that in the se-vere group,and the sTWEAK expression level was higher than that in the severe group(P＜0.05).The pre pregnancy weight,pre pregnancy body mass index,delivery weight,and weight gain during pregnancy in the good pregnancy outcome group were all lower than those in the adverse pregnancy outcome group(P＜0.05).The 24-hour urinary protein quantification in the good pregnancy outcome group was lower than that in the adverse pregnancy outcome group,and the sTWEAK expression level was higher than that in the adverse pregnancy outcome group(P＜0.05).Receiver operating characteristic(ROC)curve analysis revealed that the area under the curve(AUC)of pre pregnancy body mass index,pre pregnancy weight,delivery weight,gestational weight gain,24-hour urinary protein quantification,and sTWEAK expression levels for predicting adverse pregnancy outcomes in patients were 0.906,0.690,0.919,0.664,0.908,and 0.793,respectively.The AUC for predicting adverse pregnancy outcomes in patients by combining pre pregnancy body mass index,de-livery weight,24-hour urinary protein quantification,and sTWEAK expression level was 0.932.Conclusion Body mass index,urinary protein and sTWEAK levels during pregnancy are closely associated with the severity of pre-eclampsia and pregnancy outcomes,and these indicators may help identify high-risk pregnant women early and take appropriate interventions to improve pregnancy outcomes.