Inflammatory hematologic indices in intrahepatic cholestasis of pregnancy: a retrospective case-control study focusing on the aggregate index of systemic inflammation

Intrahepatic cholestasis of pregnancy (ICP) represents a pregnancy-specific hepatic dysfunction primarily manifesting as by maternal pruritus, increased serum bile acid concentrations, and a higher risk of poor pregnancy outcomes. Inflammatory hematologic indices calculated from standard complete blood count parameters have been considered practical and inexpensive markers for assessing systemic inflammation in obstetric conditions. This study aimed to evaluate systemic inflammatory indices, particularly the Aggregate Index of Systemic Inflammation (AISI), in individuals diagnosed with ICP and to explore their association with disease severity. This study included 186 patients diagnosis with ICP and 244 uncomplicated pregnancies of comparable gestational age. At the time of diagnosis, hematologic parameters and inflammatory indices such as AISI, neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), systemic inflammatory response index (SIRI), platelet-to-neutrophil ratio (PNR) and derived NLR (dNLR) were calculated. Patients were further stratified into mild, moderate, and severe subgroups based on total fasting bile acid (TFBA) concentrations. Multivariate logistic regression analysis was performed to evaluate whether AISI was independently associated with ICP after adjustment for maternal age, parity, and gestational age at hemogram evaluation. Neutrophil (p = 0.017), lymphocyte (p < 0.001), and monocyte (p = 0.001) counts were reduced in ICP patients, while PLR and PNR values were significantly higher (p < 0.001 and p = 0.001, respectively). No significant between-group differences were found in AISI, NLR, MLR, SII, SIRI, or dNLR values. Multivariate analysis demonstrated that AISI was not independently associated with ICP. Subgroup analysis according to disease severity revealed no significant variations in hematologic parameters or inflammatory indices (p > 0.05). AISI, which was the primary inflammatory index of interest, was not independently associated with ICP after multivariate adjustment, and most inflammatory indices showed no significant differences between patients with ICP and healthy controls. These findings suggest limited diagnostic or predictive utility of composite inflammatory indices in ICP. Although elevated PLR and PNR were observed, these changes likely reflect relative leukopenia rather than true systemic inflammation. Further large-scale prospective studies are needed.