Role of second-trimester hematological and biochemical indicators in predicting preeclampsia: a retrospective study

BACKGROUND: Abnormalities in complete blood counts (CBCs), lipid profiles, and plasma glucose levels in the peripheral blood are associated with the development of preeclampsia (PE). However, the predictive value of these indicators for PE in the second trimester remains uncertain. This study aimed to investigate the predictive potential of hematological and biochemical indicators during the second trimester for PE. METHODS: A retrospective study was conducted involving 388 pregnant women with PE and 500 healthy pregnant women who delivered between January 2022 and June 2025. Basic information, including maternal age, prepregnancy body mass index (BMI), gravidity, and parity, was collected. Blood indicators, including CBCs, lipid profiles and fasting plasma glucose (FPG) levels, were measured at 20-24 weeks of gestation. The derived parameters were calculated from these indicators. Intergroup comparisons, logistic regression and restricted cubic spline analysis were used to evaluate the relationships between these indicators and the risk of PE. A predictive model and corresponding nomogram were subsequently constructed. Receiver operating characteristic (ROC) curve, calibration curve and decision curve analyses were used to evaluate the prediction model. RESULTS: Red blood cell (RBC), hemoglobin (HGB), hematocrit (HCT), white blood cell (WBC), monocyte, lymphocyte, neutrophil, platelet, plateletcrit (PCT), triglycerides (TG), nonesterified fatty acid (NEFA), and FPG levels were elevated in the PE group, while total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) levels were decreased. The derived parameters, including systemic immune-inflammation index (SII), pan-immune inflammation value (PIV), monocyte-to-HDL-C ratio (MHR), neutrophil-to-HDL-C ratio (NHR), lymphocyte-to-HDL-C ratio (LHR), atherogenic index of plasma (AIP), atherogenic coefficient (AC), Castelli-I, lipoprotein combined index (LCI), and triglyceride-glucose (TyG), were also significantly elevated in the PE group. After adjusting for confounding factors, MHR, NHR, LHR, AIP, AC, Castelli-I, LCI, and TyG were significantly associated with the risk of PE. As these derived parameters increased, the risk of PE also increased. However, the predictive performance of single derived parameters was modest [the areas under the curves (AUCs) ranged from 0.500 to 0.701]. The prediction model included prepregnancy BMI, RBC count, platelet count, NEFA, FPG, LHR, AC, TyG, and parity. This prediction model demonstrated favorable predictive performance and calibration ability, with an AUC of 0.815 (95% CI 0.787-0.843). CONCLUSIONS: Hematological and biochemical indicators in the second trimester may serve as potential markers for PE. Integration of these indicators into routine prenatal care may facilitate early identification of high-risk pregnancies.