Early Detection of Fetal Growth Restriction: Contribution of the HALP Score and First-Trimester Maternal BMI

Background: To evaluate the predictive value of the first-trimester Hemoglobin, Albumin, Lymphocyte, and Platelet (HALP) score for fetal growth restriction (FGR), and to examine whether combining the HALP score with maternal body mass index (BMI) enhances risk prediction. Methods: We retrospectively analyzed prospectively collected data from pregnant women followed at a tertiary center between January 2023 and June 2025. A total of 176 singleton pregnancies were included, consisting of 88 women diagnosed with FGR and 88 gestational age–matched controls. First-trimester hematological parameters were used to calculate the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and HALP score. Diagnostic performance was assessed using receiver operating characteristic (ROC) analysis, and subgroup analyses were performed according to maternal BMI. Results: The HALP score was significantly lower in the FGR group than in controls (p<0.001). A HALP score ≤3.31 was associated with a more than two-fold increased likelihood of FGR (OR: 0.40, 95% CI: 0.25–0.62; p<0.001) and demonstrated the highest diagnostic accuracy, with an AUC of 0.845 (95% CI: 0.783–0.895), 80.68% sensitivity, and 78.41% specificity. Maternal BMI also influenced FGR risk. Being overweight (BMI 25.0–29.9 kg/m²) was associated with a 28% lower risk of FGR compared with women with a BMI <25 kg/m². The combined evaluation of the HALP score with BMI further improved FGR risk stratification compared with the use of BMI alone. Conclusion: The first-trimester HALP score is a valuable predictor of FGR. Combining HALP with maternal BMI enhances early identification of pregnancies at risk for FGR. Prospective multicenter studies are warranted to validate these findings. Trial Registration Number (TRN). The study protocol was registered by Selcuk University Faculty of Medicine Local Ethics Committee with a protocol number of 2025/581 and retrospectively registered.