Association between pathological stages and grades of chorioamnionitis and neonatal myocardial injury: a nested case–control study within a retrospective cohort

Background: Although chorioamnionitis (CA) is a known risk factor for neonatal complications, the epidemiological links between specific placental inflammatory stages, systemic biomarkers, and neonatal myocardial injury (NMI) remain unclear. Methods: This nested case-control study, derived from a retrospective cohort of 24,175 births, included 942 neonates (314 cases and 628 controls) delivered from 2022 to 2024. Standard and Firth's penalized logistic regression analyses identified independent risk factors for NMI. Predictive performance was evaluated using receiver operating characteristic (ROC) curves, with internal validation performed via the BCa bootstrap method. Model reliability and clinical utility were further assessed using calibration plots and decision curve analysis (DCA), focusing on the optimized Combined model 2. Results: < 0.05). Notably, FIR stage demonstrated a strong and significant association with NMI in univariate analysis. MIR stage showed the highest individual predictive accuracy (AUC = 0.814). Combined model 2 exhibited superior discriminatory power (AUC = 0.870), followed by Combined model 1 (AUC = 0.849). Internal validation confirmed the stability of these models. For the optimal Combined model 2, calibration plots revealed excellent reliability with a minimal mean absolute error of 0.02, while DCA demonstrated significant clinical net benefit across a broad threshold probability range of 0.1-0.9. Conclusion: Pathological placental MIR stage and grade are potent predictors of NMI. The synergy between PROM, SIRI, and placental inflammation underscores a continuous maternal-fetal inflammatory axis potentially involved in the development of NMI. These internally evaluated multidimensional models provide a robust framework for early risk stratification and targeted intervention for high-risk neonates.