Breastfeeding 101: Breastmilk storage guidelines

Moving on with our Breastfeeding 101 series today to talk about how you should store breastmilk. It's important to store your breastmilk in a place that is sanitary and safe. If you are pumping and storing your breastmilk at work in a common refrigerator, be sure you label it with your name or put in a bag so it is not mistaken for regular milk!

General Breastmilk Storage Guidelines

* Breastmilk can be left at room temperature (66-72°F, 19-22°C) for up to 10 hours.
* It can be stored in a refrigerator (32-39°F, 0-4°C) for up to eight days.
* If you have a single-door refrigerator with freezer section, breastmilk can be stored in the freezer for up to two weeks (due to continuous opening and closing of freezer door).
* If you have a two-door refrigerator/freezer, breastmilk can be stored in the freezer for three to four months.
* Deep freeze at constant 0°F (-19°C) for six months or longer.
* If you have any question or concern about stored milk, discard and do not feed it to the baby.

What Type of Container to Use

Refrigerated or frozen milk can be stored in hard-sided plastic or glass containers with well-fitting tops. They can also be stored in 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 the milk under warm, running water. Be careful not to bring temperature of milk to boiling point. Gently swirl the milk before testing the temperature. Swirling will also redistribute the cream. (It's normal for stored milk to separate into a cream and milk layer.) Don't shake vigorously, because it could damage some of the live components in the milk, and don't use a microwave oven to heat it.

Notes about Thawed 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.

How to Know If Your Frozen Milk Has Gone Bad

In very rare cases, frozen breastmilk can turn rancid, even if moms have meticulously expressed and frozen their milk. This happens when a mother produces milk that is high in lipase, the enzyme that breaks down fat in the milk.

Depending upon the level of lipase in her milk, some moms notice this rancid smell after their milk has cooled in the refrigerator. Others notice it after the milk has been frozen for a while. Thankfully this doesn’t happen often, and can be prevented.

It is suggested that every mother who is planning to freeze her milk should freeze some test batches of milk and thaw it out after a week or so to be sure it has not turned rancid. If it smells bad, you might need to scald the milk before freezing in the future to deactivate the lipase in your milk.

If you find that your milk it has a rancid smell after freezing and thawing it, there is a way to prevent this from occurring. Right after collecting your milk, heat it to a scald. It should be bubbling around the edges but not boiling. Then quickly cool and freeze it. Scalding inactivates the lipase.

Once the milk has acquired the rancid smell, however, treating the milk won't help. It's unknown whether this milk is safe for babies or not. However, most babies refuse it because of the taste.

If you have questions or are looking for more information on storing breastmilk, talk to your pediatrician or lactation consultant. You can also check out the Breastfeeding Answer Book published by La Leche League International.