Optimizing Human Milk Nutrient Enrichment for Preterm Infants in the NICU

Introduction Human milk is the preferred base diet for very-low-birth-weight (VLBW) infants, yet unfortified milk rarely meets preterm requirements, predisposing to extrauterine growth restriction and later morbidity, fortification is therefore standard of care. Comprehensive reviews emphasize both the benefits of human-milk-based feeding and the persistent gap in protein and mineral delivery without fortifiers. Purpose To synthesize contemporary evidence on when and how to fortify human milk, with attention to protein delivery, osmolality at the bedside, fortifier choice, and high-risk subgroups (e.g., congenital heart disease [CHD]). Method Narrative appraisal of ten recent sources (randomized trials, observational studies, bench/physiology papers, and evidence syntheses) relevant to NICU fortification practice from ۲۰۲۰-۲۰۲۵. Results Early fortification: In a masked randomized trial of extremely preterm infants, initiating fortification within the first postnatal days did not increase fat-free mass at ۳۶ weeks' PMA but improved length velocity and attenuated declines in head-circumference z-scores-supporting early, protein-attentive enrichment. Protein adequacy and individualization: Because human-milk protein content falls over time, standard fixed-dose fortification often underdelivers protein; adjustable or targeted strategies improve short-term growth (weight, length, head circumference) versus standard approaches. Practical reviews concur that many units will need pragmatic "adjustable" pathways when real-time milk analysis is not feasible. Osmolality: Individualized and modular protein additions can raise feed osmolality; adherence to _x۰۰۰۳_۴۵۰ mOsm/kg is advised to limit intolerance/NEC risk, underscoring the need for bedside mixing discipline and incremental titration. Fortifier type: Earlier observational and trial data link exclusive human-milk-based diets with lower NEC risk, yet contemporary syntheses show mixed effects when comparing human-milk-derived versus bovine-derived fortifiers; ongoing RCT work has not demonstrated decisive clinical advantages after protocol corrections. Policy and safety discussions also highlight manufacturing and contamination considerations relevant to powdered products. High-risk CHD: In infants with complex CHD, switching the fortification strategy toward extensively hydrolyzed formula for enriching expressed breast milk was associated with a reduction in NEC severity without growth penalty across hospitalization, informing tailored pathways for this subgroup. Evidence syntheses and practice frameworks converge on the necessity of fortification while calling for implementation that balances growth, tolerance, and operational feasibility. Conclusion Current evidence supports early initiation of protein-attentive fortification, with adjustable/targeted approaches when feasible, vigilant osmolality management during bedside preparation, and strategy tailoring for high-risk groups such as CHD. Priority gaps include longer-term neurodevelopmental outcomes from contemporary fortifier comparisons and pragmatic trials that integrate individualized protein targets into routine NICU workflows.