How to store, refrigerate, freeze, and use pumped breast milk

If you’re returning to work, heading to a gym class or simply want your partner to feed your little one while you have an appointment, pumping and storing breast milk might be the right option for you.

Knowing how to take care of pumped breast milk requires a bit of attention to detail and good hygiene.

Read on for tips on storing breast milk properly and preparing it when your baby is ready to feed.

Content

What are the best containers for storing breast milk?

What is the best method for storing breast milk?

How long can expressed breast milk be stored?

How long can breast milk be left out? In the refrigerator? In the freezer?

How to store breast milk in the refrigerator hygienically

How to store breast milk in the freezer

How to prepare stored breast milk

How to thaw breast milk

How to warm your stored breast milk

Why does my stored breast milk smell odd?

How to store breast milk on the go

What are the best containers for storing breast milk?

The best containers for storing breast milk should be non-toxic and free of chemicals, so anything of food-grade quality and free of Bisphenol A (BPA) should work.

(BPA is a chemical widely used in plastic containers and coatings. Many manufacturers are now phasing out BPA due to its uncertain long-term health effects and potential hormone disruption.)

Breastmilk storage bags, which are designed for freezing human milk, can be a great option. You can also use clean glass or hard BPA-free plastic bottles with tight-fitting lids. Do not use disposable bottle liners or normal plastic bags to store breastmilk.

Make sure to store breast milk in small batches to prevent waste. When your baby feeds on expressed breast milk from a cup or bottle, bacteria from his mouth can naturally end up in the milk. For this reason, it’s best to throw away any leftover, partly drunk milk within one to two hours of the feed.

What is the best method for storing breast milk?

The best method for storing breast milk is – the fresher, the better. Freshly expressed breast milk is preferable to refrigerated, and refrigerated breast milk is better than frozen. That’s because freshly expressed milk has the best bacteria-fighting properties and is higher in antioxidants, vitamins and fat than milk that has been refrigerated or frozen.

How long can expressed breast milk be stored?

If you have pumped breast milk cleanly and safely, there are different guidelines for storing it at room temperature, in the fridge, or in the freezer.

Remember, it’s not recommended to microwave frozen breast milk, so bear in mind, you might need to plan in time for the defrosting.

How long can breast milk be left out? In the refrigerator? In the freezer?

Breast milk storage varies and depends on a few factors. Follow these storage and temperature guidelines for freshly expressed breast milk for healthy term babies.

If your baby is in a neonatal intensive care unit (NICU) or special care ward, your hospital may have stricter recommendations for cleaning and storage.

If you’re refrigerating or freezing expressed milk, always label the bottles or bags with the amount and the date it was pumped, so you can track and manage your stored milk.

* Very clean conditions mean rigorously following our guidance on cleaning and sanitizing your breast pump. These guidelines for storing and defrosting breast milk are a recommendation – contact your lactation consultant or breastfeeding specialist for further information.

How to store breast milk in the refrigerator hygienically

Follow these guidelines to store expressed milk safely in the fridge:

• Refrigerate your breast milk as soon as possible after pumping.
• Store your milk in cleaned milk bottles or bags.
• When adding small quantities of freshly pumped milk to a refrigerated batch, make sure to check the temperature and let it cool if necessary. Don’t add body-temperature milk to already cooled milk.
• Store breast milk in the coldest part of the fridge – at the back, on the shelf above the vegetable compartment. Don’t keep it in the fridge door where the temperature is less consistent.

For more information see Storing Breast Milk in the Refrigerator: Tips & FAQs. 

How to store breast milk in the freezer

Some moms prefer to have a lot of back-up, so if you want to store breast milk for a longer period of time, you can also freeze it.

• Freeze your breast milk as soon as possible after pumping.
• Pumped milk can be added to already frozen breast milk, provided the milk you want to add is cooled in the fridge beforehand. Don’t add body-temperature milk to frozen milk.
• For easier thawing and minimal waste, store your milk in small quantities. These can be combined after defrosting.
• Check that your breast milk storage containers can be used in the freezer. Some products (such as glass bottles) may crack at very low temperatures. Medela breast milk storage bags are ideal for storing frozen breast milk as they save a lot of space, are freezer-proof, ready to be used and easy to label.
• Don’t fill bottles or bags to more than three-quarters full, as breast milk expands during freezing.
• Store frozen breast milk at the back of the freezer where the temperature is most consistent. Keep it away from the walls of self-defrosting freezers.

How to prepare stored breast milk

Breast milk that was stored will look different than freshly pumped milk. Stored breast milk tends to separate into layers, with the fat (cream) rising to the top. Gently swirl the bottle to mix the layers before feeding your baby.

Note: Vigorous stirring or shaking can damage some of the milk’s nutritional and protective components.

How to thaw breast milk

Thawing breast milk is not the same as defrosting other frozen food items. Take care by making sure it’s safe for your baby by following these guidelines:

• Breast milk can be defrosted in the fridge, normally in around 12 hours. Alternatively, hold the bottle or bag of frozen milk under warm running water (a maximum of 37 °C or 99 °F). Don’t leave frozen breast milk to thaw at room temperature.
• Once fully thawed, previously frozen breast milk may be kept at room temperature for a maximum of two hours or in the refrigerator for up to 24 hours.
• Don’t thaw or heat frozen breast milk in a microwave or in boiling water. These can damage its nutritional and protective properties and create hot spots that could scald your baby.
• Thawed breast milk left at room temperature should be fed to your baby within two hours or thrown away.
• Never re-freeze breast milk once thawed.

How to warm your stored breast milk

Healthy, full-term babies can drink breast milk at room temperature or warmed to body temperature. Some have a preference, others don’t seem to mind.

• To warm your milk, place the breast milk bottle or bag into a cup, jug or bowl of lukewarm water for a few minutes to bring it to body temperature (37 °C or 99 °F). Alternatively, use a bottle warmer. Do not allow the temperature to go above 40 °C (104 °F), and do not use a microwave, as this can overheat your milk.
• Gently swirl the bottle or bag, without shaking or stirring, to mix any separated fat.

Why does my stored breast milk smell odd?

You may notice that your refrigerated or thawed breast milk can sometimes smell different. This is because an enzyme called lipase breaks down fats and releases fatty acids – a process that helps prevent the growth of harmful bacteria.

Some moms report that their stored milk has a soapy or rancid smell. But if you’ve followed all the safe-storage guidelines in this article, it will be perfectly fine to use – however some babies might refuse to drink it.

How to store breast milk on the go?

If you have to transport your milk between work and home or daycare, use a cooler bag with ice packs.

For tips on pumping and storing milk on the move, read our article on travelling and pumping.