Abstract: Objective To explore the diagnostic value of the serum C-reactive protein (CRP) to prealbumin (PA) ratio, procalcitonin (PCT) to albumin (ALB) ratio, monocyte chemotactic protein-1 (MCP-1), and soluble intercellular adhesion molecule-1 (sICAM-1) in assessing the severity and prognosis of infectious pneumonia of the newborn (IPN). 
 Methods A retrospective study was conducted on the clinical data of 146 IPN infants admitted to the Department of Neonatology, Xianyang Hospital of Yan′an University from January 2020 to January 2023. Patients were divided into severe (n=84) and non-severe (n=62) groups based on the severity of the condition, and into poor prognosis (n=44) and good prognosis (n=40) groups based on prognosis. Serum levels of CRP, PA, CRP/PA ratio,serum PCT and ALB levels, PCT/ALB ratio, and levels of MCP-1 and sICAM-1 were compared among groups. Pearson correlation analysis was used to analyze the correlation between CRP/PA ratio, PCT/ALB ratio, MCP-1, sICAM-1 levels, and the severity of IPN. Receiver operating characteristic(ROC) curve analysis was used to assess the diagnostic efficiency of serum levels of CRP, PA, CRP/PA ratio, serum PCT and ALB levels, PCT/ALB ratio, and levels of MCP-1 and sICAM-1 for the severity and prognosis of IPN.  
 Results The levels of CRP, PCT, CRP/PA ratio, PCT/ALB ratio, MCP-1, and sICAM-1 were higher in the severe group than in the non-severe group, while PA and ALB levels were lower (P＜0.05). Similarly, the levels of CRP, PCT, CRP/PA ratio, PCT/ALB ratio, MCP-1, and sICAM-1 were higher, while PA and ALB levels were lower in the poor prognosis group compared with the good prognosis group (P＜0.05). Pearson analysis showed a positive correlation between the CRP/PA ratio, PCT/ALB ratio, MCP-1, sICAM-1 levels and the severity of IPN in children (P＜0.05). ROC analysis indicated that the diagnostic value of serum sICAM-1 levels was the highest for the severity of NIP, with an AUC of 0.978 (95%CI: 0.956-1.000), and also the highest for prognosis, with an AUC of 0.981 (95%CI: 0.958-1.000). 
 Conclusion The serum CRP/PA ratio, PCT/ALB ratio, MCP-1, and sICAM-1 have high diagnostic value for assessing the severity and prognosis of IPN. 

Key words: pneumonia, C-reactive protein, prealbumin, procalcitonin, albumin ,