Ultimate Guide to Breast Milk Storage

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Safety and longevity is key when storing your breast milk. You chose to breastfeed because you want to give your baby the best, but that also means you need to store it diligently to ensure it doesn’t go bad.

Of the many reasons you may choose to pump your milk and save it for later, here are just a few:

  • You can’t be with your baby all the time
  • Your baby is having trouble sucking properly
  • You are returning to work
  • You want the baby’s father or a babysitter to be able to feed
  • Your breasts are full and need to be relieved

There are several things to keep in mind when storing your breast milk, and this ultimate guide to breast milk storage will help keep your breast milk safe and your baby healthy.

Expressing Your Milk Safely

In order to store your milk, you need to express it first. This means squeezing it from your breast into a storage container in order to feed your baby later. You can do this manually or with a pump.

You can schedule these sessions to get a more regular flow going, or you may only do it in between feedings. Either way, you’ll need a few essentials to ease let down.

Bring a cover if that makes you feel more comfortable in public places. You can also use a picture of your baby to ease let down.

A breast pump makes expressing go a lot faster, but you can always use your hands if you don’t have a pump.

Use breast pads after you pump to absorb anything that may continue to leak. This will prevent odor and keep your breasts more comfortable. Also make sure you have lanolin or another sort of lubricant to prevent soreness.

A nursing bra can help you feel more comfortable when you’re not pumping, giving you some of your life back, while still making it easy to pump freely anytime.

You’ll also need bottles with caps or storage bags, a funnel to pour, and insulated cooler if you don’t have access to a refrigerator or freezer, cleaning wipes for your equipment, and hand sanitizer.


Expressing by Hand

Many times, this is more comfortable than a pump because you have complete control over the pressure you apply. It’s much slower, but it’s much more affordable.

Wash your hands thoroughly to ensure there’s no contamination in the milk you pump. Use a sterilized bottle to collect the milk as it flows. Massage gently to encourage let down and flow, and then cup your breast with your hand in a “C” shape.

By closing the open end of your hand gently, you can express your milk and adjust the pressure as needed. Release and reapply pressure at a steady pace and avoid squeezing the nipple or it will get sore.

The milk should begin dripping and then flow more steadily. Once the flow slows again, you can move on to the other side.

Expressing With a Pump

There are manual breast pumps and electric breast pumps. If you want a more affordable solution to doing it by hand, you can get a manual breast pump. They’re faster than hand expression, but not as fast as electric pumps.

For pumping with a pump, sit up straight and lean forward to ensure comfort and flow. Place your nipple in the center of the funnel. It should fit snugly but not be tight.

Begin pumping slowly or at the lowest setting for a minute or two until the milk begins to flow, then you can increase speed or turn your suction up as needed.

Suitable Containers for Storing Breast Milk

First and foremost, your containers should be BPA-free and well-sealed with either a cap or a double zip mechanism. Other than that, you can store your breast milk however it’s convenient for you. Here are some popular options:


These types of containers are usually preferred for freezer storage because they do a better job of preserving the components of your milk. The problem is they’re not as convenient. They are not flexible, and they can chip or break.

Be aware that some caregivers or daycare centers will not allow you to bring in glass.


Clear, hard-sided bottles are the safest plastic options. While you can use colored containers, some people claim that they have experienced a discoloration of their milk this way.


If you plan to use freezer bags, it’s important that you use bags specifically designed for breast milk storage. They’re less likely to contaminate your milk like generic plastic bags will, and they come with more effective seals to prevent leaks.

However, of the storage options, bags are more likely to leak than a glass or plastic container.

You also need to use caution when warming the bags because if they get submerged in warm water, water could leak into the bag and cause contamination.

The great thing about using bags is that they’re flexible. You can stack them, squeeze them in tight spaces, and store more of them at once. It’s a great solution if you’re pumping exclusively or you have a lot of breast milk to store.

If you decide to use bags, follow some extra safety tips:

  • Double bag your milk to prevent leaks. It can be really discouraging (and messy) to find that you lost a large bag of milk you so diligently pumped.
  • If you are freezing them, stack them in a hard plastic container with a lid. If they do leak, they will leak into this container and be easier to clean.
  • When warming, make sure the water level never rises above the seal. In the event the bag of milk leaks into the water, remove it and throw it away.
baby bottle

Suitable Conditions for Storing Breast Milk

No matter what container you use to store it, there are some guidelines you need to follow when storing it. A lot of it depends on how quickly you plan to use it.

  • If you plan to use the milk you pump right away, there’s no need to store it. Just put it in a sterilized bottle and feed.
  • If you are going to use your milk in 2-3 days, you are safe to store it in the refrigerator in a bag, bottle, or plastic container.
  • If you’re saving it for a later date, it’s best to put it in the freezer until you’re ready to use it.

While storing your breast milk in the freezer could result in a loss of some nutrients, it will keep your milk safe to drink and it’s still better than formula.

Many moms are overwhelmed enough with all of the rules and whether they’re doing the right thing for their baby, so there’s an easy way to remember how long breast milk will last in these conditions. Think of it in increments of six.

  • Room temperature: 6 hours
  • Refrigerator: 6 days
  • Freezer: 6 months

Room temperature

Room temperature is between 66 and 72 degrees Fahrenheit. You’re safe to keep your breast milk out at room temperature for between four and six hours before you should throw it away. Some milk will last longer, so it requires a bit of experimenting with your breast milk.

Insulated coolers and ice packs

If you’re traveling or out on a picnic and you need a way to store your milk until you need it or you get back home, you can put it in an insulated cooler with ice packs. If you do this, your milk will be safe for 24 hours.

While this doesn’t fit with our “increments of six” rule, it’s a good thing to know. As long as you get it to a refrigerator or a freezer within 24 hours, you can continue to store it normally until you need it.


If you’d like to refrigerate your breast milk for a few days, keep it as far away from the door as possible. Your refrigerator experiences fewer temperature inconsistencies at the back, which means your milk will last longer.

You can store it for a maximum of eight days at 32 to 39 degrees Fahrenheit. Again, this will vary depending on your individual milk.

Freezer compartments

If your refrigerator has a freezer compartment, you can store your breast milk there, but not for as long as a standalone freezer. This applies to smaller refrigerators with only one door. Sometimes these will have a small flap with a freezer compartment.

These don’t stay as cold and the temperature doesn’t stay as consistent as a standalone freezer, so it’s best to keep your breast milk in there for no longer than two weeks.

For a refrigerator that has a side-by-side, top, or bottom freezer, you can keep your milk in there for up to four months.

Standalone freezer

Your standalone chest freezer or deep freeze will keep temperatures much more consistent and can keep your milk safe for your baby for up to six months.

How Much Breast Milk to Store

While all containers are different sizes, you’ll have to learn how much milk your child can take in one sitting. Once you thaw your breast milk, you can’t refreeze it, so it’s wasteful to fill your containers to the brim if you can’t use it all at once.

Even if the capacity of your container is six ounces, you should only store one or two if that’s what your child will eat. Another bonus is that these smaller portions are easier to thaw.

And when your child gets to the point where they can eat more, it’s probably still best to store it in smaller portions because as it freezes, it will expand.

How to Thaw Breast Milk

When you’re ready to feed your baby, you’ll need to thaw the breast milk and possibly warm it. There are several ways to do this safely and effectively.

Thawing in the refrigerator

It’s best to thaw your breast milk slowly in the refrigerator. It could take up to twelve hours, so it’s something you can do the night before. Take out what you think your child may drink the next day and prepare it overnight.

Try your best not to thaw it at room temperature.

Under running water

If you need to speed the thawing process, you can place the container under running water. Start with cool water and gradually increase the temperature to prevent burning. Also make sure you hold the container to prevent water from getting inside.

If you are unable to use all of the milk you thawed, you may return it to the refrigerator for 24 hours, but after that, you need to throw it away. However, if your baby doesn’t finish the contents of a bottle, it must be thrown away after two hours.


If your baby doesn’t mind cold milk, you may be able to skip this step. However, some babies won’t drink it cold, in which case you’ll need to warm it carefully.

There are several ways to do this:

  • Heat water on the stove in a container slightly larger than your milk storage container. Remove the water from the stove and place your frozen or refrigerated milk in the container to warm it.
  • Use a bottle warmer.

Do not warm your breast milk in a container on the stove or in the microwave. Not only could this cause burning of the milk itself, but feeding it to your baby could cause burning in your baby’s mouth or throat.

baby with a bottle


Always label all breast milk you plan to store with the date, the volume, and the time if desired. That way you know exactly how old it is. You can use the oldest milk first and keep your stash longer.

Use a waterproof marker so it doesn’t wash off in the event that something leaks and it won’t rub off when shifting in the refrigerator or freezer.

If you’re taking these containers to daycare, also label them with your baby’s name so it doesn’t get mixed up. Believe it or not, it happens sometimes.

Adding Fresh Breast Milk to Stored Milk

Surprisingly, it is safe to add your freshly pumped milk with breast milk that’s already been stored, but it has to be from the same day.

You also need to make sure you’ve cooled your fresh milk first before adding it to something you’ve previously refrigerated or frozen.

Your fresh milk is warm, so adding it to frozen milk can cause it to thaw, rendering it unusable if you refreeze it.

Final Tips

The best time to choose how you plan to store your baby’s milk is right after you express it. Don’t wait too long or it may go bad.

When you find a container of milk that’s not labeled and you’re not sure, the best thing to do is toss it. There’s no sense in running the risk.

The safety and health of your baby is much more important than stocking up on milk that’s not safe to drink.

Sarah is a full-time freelance writer and mother of 4. She loves Jesus, cars, and coffee.