Factors associated with neonatal intensive care unit admission in preterm prelabour rupture of membranes: a retrospective study

BACKGROUND: This study evaluated the independent associations of four prespecified variables readily available at the initial assessment (gestational age at preterm prelabour rupture of membranes [PPROM], admission C-reactive protein [CRP], white blood cell [WBC] count and oligohydramnios) with NICU admission in singleton pregnancies between 34 + 0 and 36 + 6 weeks. A secondary exploratory objective was to assess the discriminative performance of a multivariable logistic regression model incorporating these four variables. METHODS: This retrospective cohort study included 345 singleton pregnancies complicated by PPROM and managed at a tertiary care centre between January 2020 and December 2025. The four prespecified variables were entered simultaneously into a multivariable logistic regression model to evaluate their independent associations with NICU admission. Antenatal corticosteroid exposure was added in a sensitivity analysis. Model discrimination, calibration and bootstrap internal validation were assessed exploratorily. Admission CRP, WBC count and oligohydramnios were not independently associated with NICU admission. The association with gestational age persisted after adjustment for antenatal corticosteroid exposure. Model discrimination was modest (apparent AUC 0.611, 95% CI 0.541-0.681; optimism-corrected AUC 0.584); after bootstrap correction, the calibration slope was 0.796 and the Brier score was 0.191. CONCLUSIONS: Gestational age at PPROM was the only prespecified variable independently associated with subsequent NICU admission, whereas admission CRP, WBC count and oligohydramnios were not independently associated with NICU admission. The exploratory model showed limited overall performance and should not be used for individual-level risk prediction.