Gestational Age–Dependent Variation and Clinical Prognostic Significance of Inflammatory Biomarkers in PPROM

To assess gestational age–dependent prognostic performance of baseline haematological inflammatory indices measured at the time of diagnosis in pregnancies complicated by preterm premature rupture of membranes (PPROM). This retrospective cohort included 313 singleton PPROM cases diagnosed between 24 + 0 and 36 + 6 gestational weeks (2021–2024) at a tertiary perinatology centre. Maternal complete blood count–derived indices—neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and delta neutrophil index (DNI)—were recorded before initiation of antibiotics, corticosteroids, tocolysis, or magnesium sulphate. Neonatal outcomes (Apgar scores, NICU admission, neonatal sepsis, and respiratory distress syndrome) were analysed across predefined gestational strata (24 + 0–27 + 6, 28 + 0–31 + 6, 32 + 0–33 + 6, 34 + 0–36 + 6). Predictive performance was evaluated using receiver operating characteristic (ROC) analysis. Latency from diagnosis to delivery decreased with advancing gestational age (p < 0.001). Prognostic performance of inflammatory indices varied by gestational window. The highest discrimination was observed at 28 + 0–31 + 6 weeks, where NLR (AUC = 0.68, p = 0.01), PLR (AUC = 0.63, p = 0.02), and SII (AUC = 0.61, p = 0.04) showed modest accuracy for adverse neonatal outcomes. At 24 + 0–27 + 6 weeks, NLR and PLR were associated with lower Apgar scores, while at 32 + 0–33 + 6 weeks, only NLR retained weak predictive value (AUC = 0.62, p = 0.03). At ≥ 34 weeks, discriminatory performance was limited. Baseline haematological inflammatory indices in PPROM demonstrate gestational age–dependent prognostic behaviour. NLR appears to be the most consistent marker, with greatest clinical relevance at 28 + 0–31 + 6 weeks. Gestational age–specific interpretation may improve risk stratification alongside standard management.