Effectiveness of Expressed Breast Milk Mouthwash for Infant Oral Hygiene

Background/Objectives: Maintaining oral hygiene in infants in neonatal and pediatric intensive care is essential for preventing ventilator-associated pneumonia (VAP). Chlorhexidine (CHX) is widely used in adults but its safety and efficacy in infants remain uncertain, and it is not recommended for children under 6 years due to rinsing difficulties and mucosal irritation risk. Expressed breast milk (EBM), rich in immunological and antimicrobial components, has been explored as a biologically appropriate alternative. This review synthesizes evidence on EBM effectiveness and safety and contextualizes it against limited indirect evidence for CHX, as no head-to-head comparative trials were identified. Methods: A systematic search of PubMed, EMBASE, Cochrane Library, CINAHL, and Web of Science (January 2015-January 2026) identified randomized and non-randomized studies involving infants ≤ 12 months receiving EBM, colostrum, or CHX for oral care. Risk of bias was assessed using RoB 2 for RCTs and ROBINS-I for non-RCTs. Due to substantial clinical and methodological heterogeneity (differing populations, dosages, frequencies, delivery methods, and outcome definitions), a narrative synthesis was performed. Results: Seventeen studies met inclusion criteria (11 RCTs, n = 1185; 6 non-RCTs, n > 3000). EBM and oropharyngeal colostrum were associated with trends toward lower VAP incidence trends (0-4%), reduced bacterial colonization, improved oral health indices, shorter mechanical ventilation time, and reduced ICU/hospital stays, with no reported adverse events. Evidence for CHX in infants was limited to a single paediatric RCT and bundled interventions, showing no significant VAP reduction and associations with mucosal irritation. The risk of bias was generally low to moderate. Conclusions: Indirect evidence suggests EBM is a potentially beneficial option for infant oral hygiene, with favourable trends for infection-related outcomes and recovery parameters. However, all EBM-CHX comparisons are indirect, and CHX evidence in infants is limited by the risk of bias and heterogeneity. High-quality head-to-head randomized controlled trials are needed to determine optimal strategies and inform guidelines.