Can you put used breast milk bottle back in fridge

At some point, every pumping mum has questions about how to store her breastmilk. We’ve put together some that will help, based on current recommendations from the CDC – but remember, if your care provider has given you guidelines specific to your situation, you should always follow those.

Storing Fresh Breastmilk

Before storing your breast milk, make sure you select a container that is sterile and rated to use for breastmilk storage. Breastmilk freezer bags typically come pre-sterilised. The Pumpables milk collection bottles are suitable for both freezer and refrigerator storage, but you will need to sterilise them first.

You can store fresh breastmilk at room temperature for up to 8 hours

Freshly expressed breast milk can be safely left at room temperature for up to 8 hours. That means you can pump into a bottle, take a break, and go back to pumping into the same bottle. However, to be on the safe side we recommend getting it into the refrigerator by about 4 hours.

You can store fresh breastmilk in a cooler bag for up to 24 hours

In a cooler bag with an ice pack, so long as the ice pack stays frozen, you can keep fresh breast milk in the cooler for up to 24 hours. This is perfect for working mums who may not have access to a refrigerator to store breast milk at work. Be sure to keep the cooler out of direct sunlight and periodically check to make sure the ice packs are still frozen. We recommend trying to transfer the breast milk to the refrigerator or freezer after about 12 hours just to be on the safe side.

You can store fresh breastmilk in the fridge for up to 8 days

Fresh breast milk can be kept in the back of the refrigerator for up to 8 days. Make sure you keep the milk in the back of the refrigerator (not the front, or in the door storage compartments) so the temperature remains consistent. Try to feed bub the milk in the first 3 or so days, and if you don’t think you’ll use it by 8 days, freeze it.

What can I do with leftover breastmilk after feeding?

If bub didn’t finish that bottle, no need to worry – follow the below guidelines to determine how long you can keep the leftover breastmilk!

If the breastmilk was freshly expressed, it can be kept up to 24 hours

Leftover fresh breast milk, as in milk that has never been frozen or refrigerated, can safely be kept at room temperature up to 2 hours, in a cooler bag with an ice pack for up to 4 hours, and in the back of the refrigerator for up to 24 hours. We recommend changing out the teat between feedings.

Previously refrigerated or frozen breast milk can only be kept up to 2 hours

Leftover breastmilk that has already been frozen or refrigerated can spoil more quickly after feeding than fresh breast milk. It can safely be kept at room temperature for up to 1 hour, in a cooler bag with an ice pack for up to 2 hours, and in the back of the refrigerator for up to 2 hours. Do not refreeze the milk! We recommend trying to use the milk right away, and changing teats between feedings. To avoid milk going to waste, try feeding bub in smaller portions (e.g. from two 4oz bottles rather than one 8oz bottle).

Heated breastmilk needs to be used right away

If breastmilk has been heated, it will need to be used right away at the next feeding or discarded. Heating breast milk changes the physical qualities of the milk, making it more prone to contamination (especially as bacteria from baby’s mouth can transfer to it from the teat). Heated milk needs to be used right away or at the next feed.

Tip: Don’t throw away breast milk past the “expiration date” – there are many alternative uses for breast milk, such as milk baths, soaps, and ointments!

You can store breastmilk in the freezer for up to a year

Frozen breastmilk can stay in a regular freezer  (-18-20°C / 0-4°F) for up to 6 months. Frozen breast milk can stay in a deep freeze (-20°C / -4°F or lower) for up to a year. If your milk is in a regular freezer and nearing on 6 months, you can transfer it into the deep freezer; and, should you have any leftover milk that’s over a year old, there are always alternative uses for it such as milk baths and breast milk soaps.

Tip: Check your freezer periodically to ensure it’s running properly. Consider investing in a freezer alarm to alert you should the freezer fail, or a universal power supply or backup generator to help should the power go out.

How to safely thaw frozen breastmilk

You can thaw frozen breast milk in the back of the refrigerator; just put the milk you want to use in the refrigerator 24 hours prior to your feeding. If you don’t use the milk within 24 hours, that’s fine; previously frozen breast milk will stay good in the back of the refrigerator for up to 48 hours.

Another method is holding the frozen bag under a stream of warm running water until the milk is thawed and reaches room temperature. Or, place it in a bowl of warm water and gently swish it around until thawed, refreshing the warm water periodically as it cools. Be careful not to heat the milk above body temperature.

Breast milk can also be thawed in a cooler bag with an ice pack. Once it’s thawed, use it right away! Thawing should take between 4 and 8 hours in this environment; check periodically.

Do not thaw breastmilk at room temperature! Do not leave the milk out to thaw at room temperature as it can spoil.

Tip: It’s unfortunate, but sometimes freezer bags or containers get damaged during the process of freezing and storing. To avoid spilling milk, check periodically for leaks during the thawing process. If you are thawing your breast milk in the back of the refrigerator or in a cooler bag, try setting it in a clean and sterile tray or container just in case.

Frequently Asked Questions

How do I know my breastmilk is still frozen?

Breast milk is still considered frozen should there be any amount of ice particles remaining in it. So, even it partially thaws, it is still considered frozen if some parts of it is frozen.

Can I refreeze breastmilk after it’s been thawed?

No. Once the milk has been thawed, it cannot safely be refrozen.

Can I microwave breastmilk?

No. Microwaving breast milk is very dangerous because hot spots can occur in the milk, which can result in serious burns when fed to infants. Overheating the milk also causes it to lose some of it nutritive value. Instead, try heating a cup of water in the microwave, then placing the breast milk container in the heated water to warm up.

Can I use bottle warmers with breastmilk?

Maybe, maybe not. It truly depends on the bottle warmer. We recommend not heating breastmilk above body temperature (37°C / 98.6°F) as it can lose its nutritive value. Many bottle warmers heat to higher temperatures than this. We encourage you to be very cautious when using a bottle warmer as those are typically designed for use with infant formula, which is not as vulnerable to overheating as breastmilk is.

Breastmilk Storage Chart

Fresh Breastmilk

Frozen Breastmilk Prior to Feeding

Fresh Breastmilk after Feeding

Previously Refrigerated or Frozen Breastmilk after Feeding

In the Freezer

For more information on breastmilk storage, preparing breastmilk and storage containers, please refer to our product manuals or contact our expert customer service team!

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