breast milk storage guidelines

Find all the answers to your questions on how to store breast milk safely

Once you start pumping, that precious breast milk has to be stored safely. Refrigerated, frozen, thawed, fresh—it can seem like a lot to keep track of! We’re breaking it all down so you can find a system that works for you. Keep in mind these guidelines are for healthy, full-term babies, as premature or immunocompromised babies may need stricter storage rules.

How long is breast milk good sitting out?

It’s best to store it in the fridge or freezer as soon as you can, but freshly expressed milk can sit out for three to four hours, even in a warm room (80 to 90 degrees Fahrenheit). At room temperature (61-79 degrees Fahrenheit), three to four hours is still ideal, but you could leave it for up to eight hours. This is great news for those times when you’re on the go and can’t tote around a cooler bag or those middle-of-the-night pumping sessions when you don’t want to trek to the fridge.

How about in an insulated cooler bag?

Breast milk is good for 24 hours in an insulated cooler bag with ice packs—great news for moms who work outside the home or travel.

… Or in a fridge?

Fresh milk that is stored in a fridge should ideally be used within three days, but it’s OK up to eight days. If the milk was previously frozen and is now thawed, use it within 24 hours. Tip: If you store fresh milk in glass bottles, use a dry erase marker to write the date it was pumped.

… Or in a freezer?

In a self-contained freezer unit of a fridge or freezer, milk is good for three to six months. In a deep freezer, it’s good for up to a full year. Tip: Label milk with the date and store it in the order it was pumped —oldest in the front to most recent in the back—so you can easily see the oldest and use it first.

Can you thaw milk and then refreeze it?

If milk is completely thawed, you cannot refreeze it. If it’s only partially thawed (ie. there are still ice crystals), you can refreeze it. Use it within the timing guidelines based on the original date it was frozen.

After frozen milk is completely thawed, how long is it good?

Thaw milk in the fridge, which takes about 12 hours, or under running water (start cool and move to warm). Once milk is completely thawed, you have to use it within 24 hours. Tip: Freeze milk in small amounts to reduce waste and cut down on thawing time.

Can you combine milk that is two different temperatures (freshly pumped and refrigerated milk)?

Ideally, you don’t want to pour warm, freshly pumped milk into cold, refrigerated milk. Best-case scenario: Chill the fresh milk and then combine the two. But if this isn’t realistic for you, or you’re far away from a fridge, you can leave the freshly pumped milk at room temperature for a few hours, then add the next pumping session’s milk to it. For more information, reach out to our team at Ashland Health and we’ll connect with you an IBCLC.

One thing we can agree on: Don’t combine fresh milk with frozen milk.

Where is the best spot in the fridge or freezer for milk storage?

Store milk in the back of the fridge or freezer, away from the door or sides. This allows it to maintain a consistent cold temperature.

How do I know if my milk has gone bad?

Spoiled milk smells and tastes very gross and sour. But moms who experience high lipase may find their milk smells soapy or tastes bad, even if it’s perfectly fine.* While some babies will refuse milk with high lipase, many babies don’t mind the taste. If the milk is truly bad, your baby won’t drink it.

Why does it seem like every source has different guidelines?

There’s a wide range between “ideal” and “acceptable” timing. The good news is breast milk is pretty resilient and can withstand lots of different storage conditions. While it’s great to use your pumped milk sooner rather than later, older milk still has plenty of benefits for your baby.

Now that you have a clear set of guidelines for how to store your milk, pump away and build that stash with confidence!