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Your breast milk — liquid gold — is likely more precious to you than many things in life right now. (Well, except your baby. They’re next-level special.)

With so many feedings in the first year and beyond, you may decide to pump and store your milk for feeding when you’re at work, enjoying a night out, or just want another option.

Overwhelmed with storage options? You’re not alone. Here’s what you need to know about keeping milk fresh and safe for your baby when it’s not coming directly from the source.

How you store breast milk has to do with the temperature of storage and whether the milk is freshly pumped or previously frozen.

Following these guidelines, which we’ve compiled from the Centers for Disease Control and Prevention, the Mayo Clinic, and the Office on Women’s Health, will ensure that your milk does not harbor bacteria that could make your baby sick. It also ensures that you retain the quality of nutrients that your milk contains.

Fresh milk can actually stay out at room temperature for a while after pumping if you plan to use it or store it soon afterward. After that, you’ll need to pop in in your refrigerator or freezer for long-term storage.

Storage type (fresh milk)Time up to which milk can be safely used
Room temperature (up to 77°F/25°C)4 hours after pumping
Refrigerator (up to 40°F/4°C)4 to 5 days
Cold packs/insulated container24 hours (or can move from cold pack to fridge or freezer up to this time)
Freezer (0°F/-18°C)6 to 12 months

What about thawed milk that was previously frozen? Different rules apply:

Storage type (thawed milk)Time up to which milk can be safely used
Room temperature (up to 77°F/25°C)1 to 2 hours
Refrigerator (up to 40°F/4°C)24 hours
Freezer (0°F/-18°C)Do not refreeze thawed milk

No matter how you’ve stored your milk, you should discard any leftovers from a feeding within 2 hours after your baby has finished.

Bear in mind that the timelines above are intended for full-term babies. If you’re pumping for a preterm baby, first of all, good for you! Research shows that human milk for preterm babies can be incredibly beneficial for their growth and development.

The time frames for using pumped milk for preemies — especially if they remain hospitalized after birth — are a bit shorter, though. If this applies to you, talk with a certified lactation consultant or your baby’s care provider for more details.

Related: 10 ways to increase breast milk supply when pumping

Always wash your hands with warm, soapy water before handling pumping supplies and breast milk. If you can’t find soap, be sure to use a hand sanitizer that’s at least 60 percent alcohol.

Tips for pumping

  • Check over your pump before using it. Look for any damaged or dirty parts, like tubing, that may contaminate your milk.
  • Once milk is pumped and in a storage container, clearly mark the number of ounces and the date and time for your reference. You might consider using a permanent marker so it doesn’t wipe off if it gets wet.
  • Always clean your pump parts thoroughly and let air dry before storage to prevent mold and other buildup of bacteria.
  • On most electric pumps, the tubing itself should never get wet. It’s too hard to ever get it dry again, which can lead to mold growth.

Tips for freezing

  • If you’re not to use freshly expressed milk right away, be sure to freeze it promptly to retain the best quality.
  • Try freezing breast milk in smaller amounts, like 2 to 4 ounces. This way, you won’t waste milk that your baby doesn’t finish. (You can always get more if needed.)
  • Leave an inch of space at the top of your container when freezing to make room for expansion. And wait to tighten the container’s cap or lid until after the milk has frozen completely.
  • Store milk in the back of the freezer, not in the door. Doing so will help protect your milk from any temperature changes.

Tips for thawing and warming

  • Always use the oldest breast milk first in your rotation.
  • Simply thaw milk overnight in your refrigerator. You do not have to warm it up for baby unless that is their preference.
  • If you’re warming the milk, be sure to keep the container closed during the process. Hold it under a stream of warm water (not hot) from your faucet. Alternatively, you may place it in a bowl of warm water.
  • Do not use your microwave to warm milk. Doing so may damage the milk and create “hot spots” in the milk that could potentially burn your baby.
  • Always test the temperature of the milk on your wrist before feeding it to your baby. If it feels hot, wait to feed until it feels comfortably warm.
  • Don’t shake milk to mix the fat with the more watery portion. Instead, swirl the milk gently to incorporate.

Related: A complete guide to pumping breast milk for your baby

There are many choices when it comes to storing breast milk in your refrigerator and freezer. What you choose is up to your preferences and your budget.

Storage baggies

Single-use storage bags are handy because they can freeze flat and stack to take up less room in your freezer. Good bags are made from food-grade, BPA- and BPS-free material that are pre-sterilized and leak resistant. You can also write any dates or other information directly onto the bag.

Many options on the market allow you to pump directly into the bag to eliminate opportunities for contamination. One potential downside to storage bags is that they are more likely to get punctured than storage bottles.

Options for storage bags include:

  • Lansinoh Milk Storage Bags allow you to pump directly into the bag. They have a double-layer zipper seal and reinforced side seams to prevent leaks.
  • Medela Milk Storage Bags have a self-standing design or can lay flat to take up less space. They’re also made from a double-layer material that resists leaks.
  • Kiinde Milk Storage Pouches have a screw-top design much like food pouches. You may even feed directly from the baggie using a special nipple and bottle system that can be purchased separately. Bonus: These baggies are recyclable.

You may even want to invest in a freezer storage organizer, like the Milkies Freeze. This small unit sits on a freezer shelf and allows you to place your most recently pumped milk on top (to freeze flat). When it’s time to feed your baby, simply grab the baggie at the bottom, which helps you use the oldest milk first.

Storage bottles and cups

If you have a bit more space, storing in bottles may be a solid choice for you. Bottles are reusable, if you’re looking to produce less waste.

You can even pump into the bottle, store in the fridge or freezer, and then warm your milk and feed directly from one container. Bottles can also go in your dishwasher for easy cleaning.

Options include:

  • Medela Milk Storage Bottles are compatible with Medela breast pumps and nipples for feeding. They include volume marks to show the number of ounces you have in each bottle. And they’re also BPA-free and dishwasher safe.
  • Lansinoh Milk Storage Bottles connect to any Lansinoh breast pump and nipple for feeding. They also have volume marks and hold up to 5 ounces of milk. Like the Medela, they’re BPA- and BPS-free and dishwasher safe.
  • Matyz Milk Storage Bottles are made from borosilicate (freezer- and boiling-safe) glass. Bottles made from glass may stain less and hold fewer odors than plastic bottles.
  • Philips Avent Storage Cups can be used alone or in conjunction with an adapter that lets you pump, store, and feed from the cups. Their screw-on lid resists leaks and they are also BPA-free and dishwasher safe.

If you go with bottles, consider getting some reusable labels to clearly write the date of when your milk was expressed on your bottles.

Storage trays

You may also want to use a tray that’s similar to an ice cube tray to store smaller amounts of breast milk. Simply pour your milk into the tray and freeze. Pop out cubes as needed.

Look for trays made from silicone or other BPA- and BPS-free, food-grade material. Trays should also have lids to protect milk from freezer burn.

Options include:

  • Milkies Milk Trays are made from food-grade plastic that’s also BPA-free. They allow you to freeze your milk in 1-ounce sticks. The frozen cubes fit into most bottles for thawing and reheating. You can then re-use the tray over and over again.
  • Sprout Cups also hold 1-ounce portions of breast milk or baby food. Instead of stick form, they’re in cubes. These trays stack for compact storage and the silicone material makes popping the cubes out super easy.

The downside with this option is that it may be tricky to keep track of when you pumped your milk. You may consider popping out the cubes and storing them in a sealed food-safe storage baggie and labeling that way.

What not to use

You shouldn’t just store your milk in any old container or ice cube tray. Whatever you use should be made from food-grade materials that are free from BPA and BPS. If your container has a recycle number 7 on it, that means it contains BPA and should not be used.

Make sure your glass or plastic lids are tight fitting. If you’re using baggies, check to make sure you’ve sealed them properly. And don’t store breast milk in the plastic liners that fit into some bottles. Same goes with zip-top sandwich bags. These aren’t meant for long-term storage.

As a note, if your baby is sick, you may want to use fresh milk instead of frozen temporarily. Pumped and stored breastmilk retains health benefits for baby, but certain cells may start to break down over time.

Additionally, fresh breast milk may contain antibodies that help prevent illness to which your baby may have recently been exposed. For this reason, you will get the most immune benefits for a sick baby by using fresh breast milk instead of frozen.

Related: 11 lactation-boosting recipes for breastfeeding moms

With enough practice, you’ll become a pro at this milk storage thing — and your baby will be able to enjoy your breast milk whether you’re in the next room or out for the evening with friends.

Still a bit overwhelmed with options? You may want to try a few different storage containers before you stock up. Take some time to see what works for your budget, your pumping collection process, and your baby’s feeding routine. You may find that a variety of options gives you the best flexibility.