Neonatal Interfacility Transport to Tertiary and Quaternary Centres: Clinical Outcomes and System-Level Determinants—A Systematic Review

Background/Objectives: Outborn neonates—those born outside tertiary perinatal centres and transferred postnatally—may experience higher mortality and morbidity than inborn infants. This systematic review without meta-analysis synthesised contemporary evidence on neonatal interfacility transfer to tertiary and quaternary neonatal centres, focusing on mortality, major morbidity, physiological instability, prognostic tools, and organisational determinants. Methods: Four electronic databases (PubMed/MEDLINE, Scopus, Web of Science, and the Cochrane Library) were searched for English-language publications from January 2010 to December 2025. Study selection and data extraction were performed independently by two reviewers, with disagreements resolved by consensus. Narrative synthesis followed PRISMA 2020 and SWiM principles. Of the 2456 records identified, 44 publications were retained: 31 primary studies and 13 contextual or methodological sources. Results: Across the primary evidence, outborn status was generally associated with higher mortality and major morbidity, particularly among very preterm infants, although effect magnitude varied across healthcare systems. Hypothermia, respiratory deterioration, and haemodynamic instability were recurrent transport-related complications. Specialised teams, standardised stabilisation, and thermal-management bundles were associated with better physiological stability. TRIPS and TRIPS-II showed prognostic utility. Conclusions: Predominantly observational evidence suggests that neonatal transport outcomes reflect interactions between biological vulnerability, transport-related stress, and system organisation. Strengthening regionalised transport pathways and standardising stabilisation practices may improve outcomes, but causal inference remains limited.