Glass or hard plastic containers are the best storage containers for human milk, especially if it is to be frozen and stored for weeks or months. Special storage bags designed for storage of human milk are available from certain breast pump manufacturers. Freezing may cause the seams of disposable bags created for bottle feeding to split, but double-bagging may prevent this problem. If using bags, squeeze the air from the top before sealing tightly with a twist-tie or other clamp. Fasten the clamp at least one inch beyond milk level to allow for expansion with freezing. Place storage bags upright in another container or the milk will leak.
If you pumped both breasts at once and the amount of milk obtained will fill one bottle or bag no more than two-thirds full, you may combine the contents in a single container by carefully pouring the milk from one container into the other. Store only two to four ounces per container. It is easier to thaw a second container of milk than to watch your valuable milk be poured down the drain. Label each collection container with the date and any medications you have taken.
The following guidelines are for healthy, term infants. Storage guidelines may be different for premature or high-risk infants. Consult your baby's doctor for specific instructions.
"Fresh" breast milk contains the most active anti-infective properties, followed by refrigerated, and then frozen breast milk.
Unrefrigerated fresh milk may be left at room temperature of 77 degrees Fahrenheit (25 degrees Celsius), but it must be used within eight hours.
It probably is better to refrigerate fresh milk when it is not going to be used within 60 minutes. The refrigerator should be at a temperature of 32 to 39 degrees Fahrenheit (0 to 4 degrees Celsius). Do not freeze milk for a high-risk baby when that milk has been refrigerated for more than 24 to 48 hours.
If refrigerated milk will not be given within one week, freeze it for later use. Milk can be frozen for approximately:
Up to two weeks if the freezer compartment is within the refrigerator. (You must open the refrigerator door to reach the freezer with this model.)
Three to six months in a freezer that is part of a refrigerator unit but has a separate door.
Six to 12 months in a separate, -4 degrees Fahrenheit (-20 degrees Celsius) "deep" freezer.
To keep milk cool when a refrigerator is not immediately available, or to transport refrigerated or frozen milk, place it in an insulated bag or cooler with a frozen cold pack.