Reported Factors Associated With Hearing Loss in Infants Admitted to Neonatal Intensive Care Units: A Scoping Review of the Evidence and Its Limitations

ABSTRACT Background Hearing loss (HL) is far more common in neonatal intensive care unit (NICU) graduates than in well‐baby populations. Although many broadly defined ‘risk factors’ have been reported, their causal relevance remains unclear. Objectives We conducted a scoping review to synthesise reported factors for HL among NICU and special care nursery (SCN) infants. We then assessed the strength of the supporting evidence. Data Sources Embase, Medline, APA PsycInfo, and Web of Science were searched (1 Jan 2015–11 Mar 2025). Study Selection and Data Extraction We included studies that reported factors associated with HL among NICU/SCN graduates. Commentaries, conference abstracts, letters, and case reports/series were excluded. Data were extracted independently by two reviewers using a piloted Excel spreadsheet. Synthesis We followed PRISMA‐ScR guidelines. Reported factors were classified into categories and broad domains. We summarised adjusted associations and appraised the evidence, including indications of causal support. Results Ninety‐six studies met the inclusion criteria, identifying 141 unique factors which were organised into six domains and 32 categories. No eligible study focused specifically on SCN infants. The most frequently studied factors were birthweight (38.5%), hyperbilirubinemia (25.0%), Apgar score (24.0%), sepsis (21.9%), and sex (20.8%). Effect estimates were infrequently reported, and evidence within categories was highly heterogeneous. Support for causal interpretation was identified in four studies (4.2%), including those of hypoxia‐ischemia, encephalopathy with seizures, postnatal CMV infection, and higher frequency of vancomycin dosing. Evidence was limited by the small number of confounder‐adjusted analyses, prospective or trial designs, and studies with adequate follow‐up. Conclusions The literature on NICU‐related hearing loss includes many repeatedly reported associated factors, but the evidence supporting their causal role remains limited and heterogeneous. As a result, many reported factors cannot yet be interpreted as credible prevention targets. Better‐designed studies for estimating causal effects are needed to support prevention‐oriented decision‐making.