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 degrees C. STUDY DESIGN Fresh milk samples (n = 36) were divided and stored at 4 degrees 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 degrees 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 x 10(5) colony-forming units per mL), pH (7.21 to 6.68), white blood cell counts (2.31 to 1.85 x 10(6) 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.