Refrigerator Storage of Expressed Human Milk in the Neonatal Intensive Care Unit

Objective

To provide recommendations for refrigerator storage of human milk, the overall integrity (bacterial growth, cell counts, and component concentrations) of milk was examined during 96 hours of storage at 4°C.

Study design

Fresh milk samples (n = 36) were divided and stored at 4°C for 0, 24, 48, 72, and 96 hours. At each time, pH, white cell count, and osmolality were measured and additional samples were stored at −80°C until analyzed for bacteria and concentrations of lactoferrin, secretory (s)IgA, fat, fatty acids, and protein.

Results

There were no significant changes for osmolality, total and Gram-negative bacterial colony counts or concentrations of sIgA, lactoferrin, and fat. Gram-positive colony counts (2.9 to 1.6 × 10⁵ colony-forming units per mL), pH (7.21 to 6.68), white blood cell counts (2.31 to 1.85 × 10⁶ cells per mL), and total protein (17.5 to 16.7 g/L) declined, and free fatty acid concentrations increased (0.35 to 1.28 g/L) as storage duration increased, P < .001.

Conclusions

Changes were minimal and the overall integrity of milk during refrigerator storage was preserved. Fresh mother's milk may be stored at refrigerator temperature for as long as 96 hours.

NICU, Neonatal Intensive Care Unit, sIgA, Secretory IgA