Association of patent ductus arteriosus and severity score with neonatal pulmonary hemorrhage and mortality in very preterm infants: a retrospective cohort study

To evaluate the association of patent ductus arteriosus (PDA) with the occurrence of neonatal pulmonary hemorrhage (NPH) and post-hemorrhage mortality in very preterm infants (< 32 weeks gestation). This retrospective cohort study included 482 very preterm infants (gestational age < 32 weeks) admitted between January 2019 and October 2025. The Patent Ductus Arteriosus Severity Score (PDAsc) was calculated for those diagnosed with PDA. Univariate and multivariate logistic regression analyses were performed to identify factors associated with NPH and post-hemorrhage mortality. Nomograms for risk assessment were constructed and internally validated using the bootstrap method. SHAP analysis was conducted to enhance model interpretability by visualizing the impact of individual predictors on outcomes. Of the 482 infants, 93 (19.3%) developed NPH, among whom 42 (45.2%) died. In the entire cohort, factors independently associated with NPH included lower gestational age, lower birth weight, lower 5-minute Apgar score, premature rupture of membranes (PROM), and hemodynamically significant PDA (hsPDA). SHAP analysis revealed that gestational age contributed most to the risk assessment of NPH, followed by hsPDA and birth weight, providing intuitive visualization of individual risk contributions. In infants with NPH and PDA ( n = 81), multivariate analysis identified a higher PDAsc as independently associated with in-hospital mortality (OR = 3.614, 95%CI: 1.918–6.812). The nomogram for assessing the risk of NPH in the PDA subgroup showed an AUC of 0.858 (95%CI: 0.812–0.904), with a bootstrap-corrected value of 0.837. In very preterm infants, hsPDA is independently associated with NPH. Among those with PDA who develop NPH, the PDAsc is strongly associated with in-hospital mortality, which may aid in early identification of high-risk infants and individualized management, pending external validation in larger cohorts.