Storing milk in 2-4 ounce amounts may reduce waste. Refrigerated milk has more anti-infective properties than frozen milk. Cool milk in refrigerator before adding to frozen milk. All milk should be dated before storing.

Human milk can be stored:

– At room temperature (66-72°F, 19-22°C) for up to 10 hours
– In a refrigerator (32-39°F, 0-4°C) for up to 8 days – in a freezer compartment inside a refrigerator (variable temperature due to the door opening frequently) for up to 2 weeks
– In a freezer compartment with a separate door (variable temperature due to the door opening frequently) for up to 3 to 4 months.
– In a separate deep freeze (0°F, -19°C) for up to 6 months or longer.

What Type of Container to Use:

Refrigerated or frozen milk may be stored in:
– hard-sided plastic or glass containers with ill-fitting tops
– freezer milk bags that are designed for storing human milk
Disposable bottle liners are not recommended.

How to Warm the Milk:

Thaw and/or heat under warm, running water.
Do not bring temperature of milk to boiling point.
Gently swirl milk before testing the temperature. Swirling will also redistribute the cream into the milk. (it is normal for stored milk to separate into a cream and milk layer.)
Do not use a microwave oven to heat human milk.

Thaw Milk:

If milk has been frozen and thawed, it can be refrigerated for up to 24 hours for later use. It should not be refrozen. It is not known whether milk that is left in the bottle after a feeding can be safely kept until the next feeding or if it should be discarded.

According to THE BREASTFEEDING ANSWERR BOOK, research indicates that human milk has previously unrecognized properties that protect it from bacterial contamination. One study, Barger and Bull 1987, found that there was no statistically significant difference between the bacterial levels of milk stored for 10 hours at room temperature and milk that had been refrigerated for 10 hours. Another study, Pardou 1994, found that after 8 days of refrigeration some of the milk actually had lower bacterial levels than it did on the day it was expressed.