Milk Storage: How Do I Store Pumped Milk?

Pumping and storing breast milk is ideal if you're returning to work or leaving your baby with your partner or a caregiver for a few hours. Breast milk is perishable, so it's important to know how long it can last in each of its states: fresh, refrigerated and frozen.

How long will fresh breast milk last at room temperature?

 

Milk that has been pumped from the breast can be left at room temperature for 6 to 10 hours. So if you pump a bottle and head out for the day with your little one, just put the bottle in your purse or diaper bag—no freezer packs necessary. Or if your baby is staying home, you can leave the bottle on the kitchen counter for whoever is looking after him.

While it's safe for breast milk to sit out for a few hours, make sure your home is at a comfortable temperature and the bottle isn't put near heaters or radiators.

If you're concerned the milk has been left out too long, don't worry—breast milk that has gone off smells bad, just like spoiled milk from a carton. And most babies won't take sour breast milk; they'll either push the bottle out of their mouth or give you a hard time taking it.

How long should I store breast milk in the refrigerator?

Refrigerated breast milk will last up to 8 days. On Day 8, smell the milk before using it to ensure that it isn't part of the minority that turns bad before that time. If you haven't used the milk by Day 8, move it to the freezer.

A good thing to do with refrigerated milk is to put it in the back of your fridge, away from temperature fluctuations caused by opening and closing the door.

Can I store breast milk that has been warmed but that my baby didn't finish?

The research is mixed on this issue, but generally it's fine to put the leftover milk back in the refrigerator to use again later. However, the milk should be used quickly, within a day, and only once more. Always smell it before re-warming to make sure it hasn't gone bad. And if your baby doesn't finish it the second time, dump it out.

How long can I freeze breast milk?

Frozen milk can stay in the freezer for months. If you keep it in the back of the freezer and it stays frozen solid it should be fine for up to a year, and at the very least for 6 months.

However, if you have a freezer that is only accessible by opening the refrigerator door, such as the small models found in offices, it's best to store breast milk for only 2 months. Again, always smell it before using it; you don't want to throw out perfectly good breast milk.

The best way to store frozen breast milk is in special freezer bags designed for this purpose. You can freeze it in non-glass bottles, but this takes them out of circulation and means regular washing. You can buy breast milk storage bags at most drugstores and specialty baby stores.

Tips for storing frozen breast milk:

  • It's best to freeze breast milk in small batches, so around 2 to 4 ounces. If you defrost a larger bag, say 7 ounces, and your baby doesn't finish it, you might have to dump it, since thawed breast milk doesn't have as long a shelf life as fresh or refrigerated. If your baby drinks 4 ounces and is still hungry, it's easy to thaw another smaller bag to top up the feeding.
  • Always label the date the milk was pumped as well as the volume (most breast milk freezer bags come with a label area). This is important not only for storage issues but also so you'll know the correct amounts. The freezer expands the milk a bit, so a 3-ounce bag may end up looking more like 5 ounces after it's been frozen.
  • Frozen breast milk can be used at any stage of your baby's life, no matter when it was pumped. So if you pumped the first week and stored it in the freezer, it's OK to give it to your now five-month-old, even if it has some colostrum in it and is a different color than your mature milk.

What's the best way to thaw frozen breast milk?

The short answer is slowly. If you don't need the milk right away, put it in the refrigerator and it should be thawed in a day.

If you need the milk immediately, here are two faster ways to thaw it:

  • Submerge the breast milk bag in a bowl of warm water. Change the water several times while it's thawing, since the milk will act like an ice cube and cool the water quickly.
  • Microwave a mug of water and submerge the breast milk bag in the hot water. Never microwave a frozen bag of milk, since the microwave kills many of the healthful properties of the breast milk and can create hidden "hot patches" that can remain even if you shake it in the bottle, which can burn your baby's mouth.

Keep in mind that thawed breast milk needs to be used within a day or two. Its shelf life is much shorter than fresh or refrigerated.

What can I do if my baby rejects thawed breast milk?

Some women find that their thawed breast milk smells soapy and their babies aren't keen to take it. This could be due to a high amount of the enzyme lipase in it.

If you're baby won't drink thawed milk, try these tips:

  • Bring your fresh just-pumped breast milk almost to a boil slowly. Immediately put it in a container on a very cold ice bath. If you freeze it after this, there should be no soapy smell.
  • Sometimes it's good to just persevere. Some picky babies eventually come around and will drink the thawed breast milk. Always try this method first, since boiling the milk is time consuming.

Tips for success:

Remember, fresh is best—every temperature drop in breast milk affects some of its healthful properties. Always try to use fresh just-pumped milk, and then refrigerated over frozen.

This information is courtesy of Bravado Designs, the brand synonymous with women's breastfeeding success for 18 years.

Source: Heather Kelly is an International Board Certified Lactation Consultant (IBCLC) who also sits on the Bravado Breastfeeding Information Council Heather has been practicing in New York City since 2001.

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Heather Kelly
Heather is an International Board Certified Lactation Consultant.
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