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

https://doi.org/10.1016/j.jpeds.2009.07.023Get rights and content

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.

Section snippets

Methods

Mothers of term and preterm infants in the NICU were asked to collect 80 mL of milk using an electric breast pump (Ameda SMB Electric Breast Pump, Piqua, Ohio) directly into breast milk storage containers (Medela, Inc., McHenry, Illinois) from either or both breasts. Mothers gave their fresh milk to the research team who aseptically separated the 80-mL sample into 5 milk storage containers that either were studied immediately (at time point 0) or stored in the NICU at refrigerator temperature

Results

Milk was obtained at a median of 28 days postpartum (range, 7 to 150 days) from mothers who delivered at a median gestational age of 32 weeks (range, 25 to 41 weeks). The average time between milk collection and first analysis was approximately 2.4 ± 1.2 hours. The cumulative numbers of refrigerator “openings” at 24, 48, 72, and 96 hours were 21 ± 8, 38 ± 15, 56 ± 21, and 71 ± 27, respectively. Milk pH declined significantly, from 7.21 to 6.68 over 96 hours of storage (Figure 1). White blood

Discussion

This multifactorial approach determined that the integrity of fresh mother's milk was not affected by 5 days of storage at refrigerator temperature. We observed how often the refrigerator was opened each day, yet the temperature was maintained and verified by serial monitoring. The lack of significant increases in bacterial colony counts is important. Indeed, the decline in Gram-positive colony counts is indicative of an active host defense system in the milk. Although the changes in bacterial

References (12)

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The authors declare no conflicts of interest.

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