Frequently Asked Questions

Once the power is back on, check the condition of your stored breast milk. Frozen breast milk that has started to thaw but still contains ice crystals can be refrozen. If your breast milk has completely thawed but still feels cold, put it in the refrigerator and use it within the next day or throw it away.

Is Reheating Breast Milk Safe?

For moms returning to work or just ready for a bit of flexibility in their breastfeeding routine, understanding how to safely store and reheat pumped breast milk is important.

With all the work that goes into building a stockpile of breast milk, you’ll want to make sure that all those nutrients and immunity-boosting properties are properly preserved.

You can do that by following best practices for storing and reheating breast milk.

Choose the oldest milk to thaw first. Frozen milk should be thawed overnight in the refrigerator. You can also place it under a slow, steady stream of cool running water. To heat the milk, slowly increase the temperature of the running water to bring it to feeding temperature.

If you’re reheating milk that’s been refrigerated, use warm running water to take off the chill. You can also heat a pot of water on the stovetop, and place the bottle or bag into the water.

Don’t heat the breast milk directly on the stovetop, and never make breast milk hot enough to boil. If you’re using refrigerated milk, you might try offering it to your baby before warming. Some babies are fine with cool milk.

Never use a microwave to heat breast milk. Some research suggests that microwaving breast milk may decrease some of its nutritional content.

There’s also a risk of scalding because microwaves heat liquids unevenly, which can cause hot spots within the container. These hot spots could burn your baby as you’re feeding them.

Note that refrigerated breast milk may look separated, with a thin cream layer on top and a watery milk layer beneath. This doesn’t mean that the milk has spoiled or gone bad. Just gently swirl the container or massage the bag to redistribute the cream before feeding your baby.

Thawed milk may sometimes have a soapy odor or taste, which is caused by the milk fats breaking down. This milk is still safe to feed to your baby, though there is a possibility that they won’t drink it. If that’s the case, try reducing the length of time you store your expressed milk.

According to La Leche League, pumped breast milk should be frozen or refrigerated immediately after expressing. Store your expressed breast milk in 2- to 4-ounce amounts in milk storage bags, or glass or stiff-plastic containers with tops that fit tightly.

Note that milk storage bags are specially designed for expressed breast milk. Don’t substitute standard kitchen storage bags or disposable bottle liners. Not only are these bags less durable and prone to leaking, the risk of contamination is higher.

Some types of plastics can destroy the nutrients in breast milk, too. Before sealing, squeeze out the air in the bag.

If you use plastic bottles, be sure to avoid containers that have BPA (bisphenol A). These containers can be identified with a 3 or a 7 in the recycling symbol.

Instead, opt for those made with polypropylene, which will have a 5 in the recycling symbol, or the letters PP. If you’re worried about the leaching potential of chemicals from any plastic container, opt for glass.

Before putting breast milk into any container, make sure to wash it with hot, soapy water. Rinse well, and leave to air dry before using it. Or, use a dishwasher. Take a moment to inspect your containers before adding milk.

Never use a bottle that looks damaged in any way, and discard any milk that has been stored in a damaged container. Make sure you also always wash your hands before expressing or handling breast milk.

When filling containers, leave space at the top. Breast milk expands as it freezes, so leaving about an inch at the top will allow for this expansion.

Label your bags or containers with the date expressed and the amount of milk. Also write your child’s name if you may be giving it to a child care provider. Store your bags or containers with expressed breast milk at the back of the refrigerator or freezer. That’s where the air will stay the most consistently cool. If you’re using bags, put them into another sealed container for storage.

If you have freshly expressed milk, the Mayo Clinic advises that you can add it to refrigerated or frozen milk if you expressed it earlier in the same day.

If you do so, make sure to allow the newly expressed milk to cool in the fridge before adding it to the already chilled or frozen milk. Adding warm breast milk to frozen milk can cause the frozen milk to thaw slightly, which can increase chances of contamination.

Frequently Asked Questions

Many factors can affect how long breast milk can be stored in various locations, such as storage temperature, temperature fluctuations, and cleanliness while expressing and handling breast milk. These factors make it difficult to recommend exact times for storing breast milk in various locations.

Does the temperature of the room matter if I plan to leave breast milk on the counter until I use it?

Yes. If you live in a warmer climate or keep your home at a warmer temperature, you should place breast milk in the refrigerator if it will not be used within a few hours. Breast milk does not spoil as quickly at cooler temperatures.

What is the recommended method to store and serve breast milk that is leftover from a feeding?

If your baby did not finish the bottle, the leftover breast milk can still be used within 2 hours after the baby is finished feeding. After 2 hours, leftover breast milk should be thrown away. To avoid wasting unfed milk, consider storing, thawing, and warming milk in smaller amounts.

How can I determine the temperature of my refrigerator and freezer?

Your refrigerator should be 40°F or below, and your freezer should be 0°F or below. If your refrigerator/freezer thermostats do not show the temperatures, use inexpensive freestanding appliance thermometers external icon . Even if your refrigerator/freezer do show the temperatures, appliance thermometers may be important if you lose power or have mechanical problems.

If I move stored breast milk that has been in a kitchen freezer to a deep/chest freezer or vice versa, do the storage recommendations change?

No. You can count the age of the milk from the first time that it was frozen, regardless of when it was moved. As long as the temperature of the freezer is 0°F or below, it does not matter whether it is a kitchen freezer or a deep freezer. Breast milk can be stored in the freezer (at 0° F or colder) for up to 12 months, although using it within 6 months is best. The temperature of kitchen freezers is typically 0° F and although deep freezers or chest freezers may be able to operate at a temperature colder than 0° F, both types of freezers fall within the guideline of keeping frozen milk at a temperature of 0° F.

Moving frozen breast milk between freezer locations should be done quickly to ensure that the milk stays frozen. It may be useful to pack the frozen breast milk on ice packs while transporting the milk from one location to another.

If I don’t use breast milk stored in the refrigerator within a few days, can I still freeze it to use later?

After 4 days of refrigeration, your breast milk should be used or thrown away. Breast milk has properties that slow the growth of bad bacteria. These properties begin to decline after a few days of refrigeration. If you think you won’t use breast milk within a few days, the sooner you freeze it, the better.

Can I mix freshly expressed breast milk with older breast milk?

Mixing freshly expressed breast milk with already cooled or frozen milk is not advised because it can rewarm the older stored milk. It is best to cool freshly expressed milk before combining it with older, previously cooled or frozen milk. It is also important to consider storage duration guidelines for breast milk. For example, if combining cooled milk pumped on different days, the duration of storage should be based on when the older milk was first stored.

The power went out! Do I have to throw out all of my stored frozen breast milk?

Your breast milk may still be safe, but it depends on how long the power is out and how defrosted or warm the breast milk becomes. Freezers, if left unopened and full during a power outage, will keep food safe for about 48 hours (about 24 hours if half full). When freezers are full, the other frozen items help keep the freezer colder longer. The refrigerator will keep food cold for about 4 hours if it is unopened. While the power is out, keep the freezer and refrigerator doors closed as much as possible.

Once the power is back on, check the condition of your stored breast milk. Frozen breast milk that has started to thaw but still contains ice crystals can be refrozen. If your breast milk has completely thawed but still feels cold, put it in the refrigerator and use it within the next day or throw it away.

Where can I store my breast milk at work?

Expressed breast milk is a food and may be stored alongside other foods in any refrigerator that is appropriate for food storage. Employers, coworkers, cleaning staff, other family members, and childcare providers should not consider or treat breast milk as a biohazard. Storing breast milk in a shared refrigerator and washing pump parts in community break rooms are unlikely to pose health risks (sanitary or safety issues); however, it is important that the breast pump equipment be cleaned, dried, and stored in a sanitary (clean) environment to protect the equipment (and expressed breast milk) from contamination.

What are the recommendations for properly storing expressed breast milk while traveling?

Traveling by air?

• You are allowed to carry more than 3.4 ounces of breast milk in your carry-on bag, as well as ice and gel packs.
• The Transportation Security Administration (TSA) external icon has specific screening procedures for anyone traveling with breast milk.
• Consider keeping a copy of the TSA regulations in your carry-on bag.

Expressed breast milk may be stored and transported in an insulated cooler bag with frozen ice packs for up to 24 hours, or else frozen in dry ice (follow safety precautions when handling dry ice external icon ). Once breast milk is cooled, it should remain cool until it is consumed. Breast milk that has been transported in an insulated cooler bag with frozen ice packs can then be refrigerated or frozen.

Depending on the destination, if no reliable breast milk storage is available, a mother traveling with expressed breast milk could consider using temperature-controlled shipping to transport breast milk or discarding her expressed breast milk. Continuing to express breast milk regularly will help a mother to maintain her breast milk supply until she and her nursing infant or child can be reunited. Visit CDC’s Travel Recommendations for the Nursing Mother webpage to learn more.

How to thaw my breast milk?

If you’re asking yourself, “Can I thaw my breast milk?” this article is for you. Remember to read to the end so you don’t miss anything. Thaw means to miss the icing or freeze of the substance. This is different from cooling, and Freezers can do this. As a mother who breastfeeds, you know how hard it can be to pump and store your milk correctly. Safe storage rules are hard to follow when you’re half asleep after a 3 a.m. feed or running late for a 10 a.m. meeting, so you don’t want that valuable liquid gold to go to waste. What happens if you heat a bottle of expressed milk that was kept in the fridge and your baby doesn’t finish it? The answer will depend on several things. Learn more by reading on.

Can warmed breast milk be refrigerated again?

If you warm breast milk, you can give it to your child once it is at room temperature. However, if it is refrigerated again for up to 24 hours, your baby can finish the feeding within that time. If your baby does not finish a feeding, you should throw away the leftover breast milk in the bottle. Although it’s not well known, refrigeration can slow the growth of some bacteria. Many mothers rewarm previously refrigerated milk without a problem. However, you should always check to see if your milk has spoiled before heating it again.

Why Should I Let My Breast Milk Defrost?

1. ⒈Freshness and nutrition are at their best when breast milk is frozen within an hour of being pumped. This locks in all the milk’s freshness and nutrients while they are at their best. They will stay that way until you take the milk out of the freezer.
2. ⒉Natural and free of preservatives: Milk that has been frozen needs not to have preservatives because freezing is a natural way to store food.
3. ⒊Flexibility: Breastfeeding your child every time can be stressful, but you can warm up milk that has already been thawed and give it to your child. Also, this will help your child get to know more people. While busy or at work, someone else can feed your child.
4. ⒋You can keep it for a long time: Breast milk that has been thawed can also be held in the freezer for six months to a year without losing its nutrition or freshness.

How to freeze breast milk

Here are some safe ways to freeze breast milk:

• ● Put your breast milk in the freezer as soon as possible after expressing it.
• ● Pressed milk can be added to breast milk that has already been frozen, as long as the milk you want to add has been cooled in the fridge first. Don’t mix frozen milk with milk that is at room temperature.
• ● Store your milk in small amounts for easier thawing and less waste (less than 60 ml). After defrosting, these can be mixed
• ● Make sure your breast milk storage containers can go in the freezer. Some products, like glass bottles, can break at very low temperatures.
• Don’t fill bottles or bags more than three-quarters full because breast milk expands when it freezes.
• ● Store breast milk is frozen at the back of the freezer, where the temperature stays the same. Please keep it away from the walls of freezers that can defrost on their own.

Getting frozen breast milk out of the fridge

Breast milk can take up to 12 hours to thaw in the fridge, so plan. You might want to put a full day’s worth of frozen breast milk in the fridge each night, so it’s ready to use the next day. To thaw frozen breast milk in the refrigerator, do the following:

1. ① Take the frozen breast out of the bag or bottle and put it on a plate.
2. ② Put it inside the fridge.
3. ③ Wait until the frozen milk goes back to being liquid.
4. ④ Use the milk within 24 hours after it has been thawed.
5. ⑤ Breast milk that has been thawed for 24 hours should not be frozen again.

Breast milk can be thawed in a bowl of warm water

You can quickly thaw frozen breast milk in a bowl of warm (not hot) water. This method takes about 20 minutes if you watch the water and change it when it gets too cool. This is how:

1. ⒈Pour warm water into a bowl or pan.
2. ⒉Put the frozen breast milk container into the water. Please make sure the water level in the breast milk bottle is below the top to keep it from getting dirty
3. ⒊When the water cools, pour it out and fill it with warm water.
4. ⒋Keep doing this until the breast milk isn’t frozen anymore.
5. ⒌Once the milk is no longer frozen, put it in the fridge or keep warming it up so your child can drink it.

Letting frozen breast milk melt in moving water

The quickest way to get breast milk out of the freezer is to hold it under a faucet with warm water running. You can do the following:

1. ⒈Put the container (or bag) under cold running water to start.
2. ⒉Gradually raise the temperature of the running water, but don’t let it get too hot.
3. ⒊Hold the container under warm water until the milk is no longer frozen.

Breast milk that has been thawed doesn’t always smell very good. It can also taste like soapy metal.

It doesn’t mean the milk is sour if this happens. The milk smells and tastes strangely ominous because it has an enzyme called lipase. Lipase breaks down the fats in milk while it is being stored. You can still give the milk to your baby, but if your child doesn’t like how it tastes, they may not drink it.

Getting thawed breast milk ready to use

You can give your baby breast milk that has been thawed right out of the fridge, or you can warm it up to room temperature or body temperature. If you need to warm up your breast milk, you can put it in a bowl of warm water for a few minutes, hold it under warm running water, or use a bottle warmer.

You shouldn’t heat breast milk in the microwave or a pot of boiling water on the stove. It’s essential to warm your breast milk properly so your baby’s mouth and throat don’t get burned.

Once the milk is warm, give the container a gentle shake to mix any layers that may have separated. Check the milk’s temperature before you provide it to your baby. Pour a few drops on the inside of your wrist to do this. It should feel neither too hot nor too cold. It shouldn’t be very warm or freezing.

The Risks of Using the Stove and Microwave

It would be best if you didn’t use a microwave oven to thaw a container of frozen milk or warm it up. Some of the healthy things in breast milk can be destroyed by the high heat from a microwave. Microwaves can also heat in a way that isn’t even, which can cause hot spots in the breast milk. Your baby’s mouth and throat can get burned by these hot spots.

Heat breast milk on the stove is also not a good idea. Putting a bag or container of breast milk in a pot of boiling water on the stove can cause it to get too hot. Overheating milk can kill the good things in it and make it too hot for your child to drink.

How to Safely Handle Breast Milk That Has Been Warmed

If you know how to handle and use your breast milk safely, it won’t go bad or become a place where bacteria can grow. Here are some tips:

• Once the breast milk has been warmed, you can give it to your child immediately or put it back in the fridge for up to 24 hours.
• Warm breast milk shouldn’t be left out at room temperature.
• It shouldn’t be frozen again.
• If your baby doesn’t drink all the breast milk in the bottle, you should throw it away.