Breast Milk Storage Guidelines – Is Your Stored Breast Milk Safe to Drink?

How long can you store breast milk at room temperature? Can you mix newly pumped milk with one you just pumped a few hours ago? Can you put thawed milk back in the freezer? These are just some frequently asked questions breastfeeding mums have about breast milk storage. 

Whether returning to the office or planning a dinner date with your friends, most new mamas eventually need a break from breastfeeding. This is where breast pumps come into the picture.

They allow new mums the freedom to feed the baby on demand, even when they are back to their routines and away from the little ones. 

But don’t you hate it when your expressed breast milk goes bad or the baby doesn’t finish the amount you thawed and you have to discard that precious liquid gold? I know I felt so bad every time it happened. Every drop counts, don’t you agree?

That’s why we need to be very smart and careful with how we pump, store and thaw our breast milk. This is to make sure all our time and effort spent power pumping does not go to waste. More importantly, effective and safe storage of breast milk ensures that only the best is given to your baby. 

Breast Milk Storage Guidelines

Freezing breast milk is a great way to keep it safe and easy to access, but you need to follow storage guidelines to keep it safe and of the best quality for your baby.

Here are some of the key points to remember, in a nutshell:

1. Before expressing or handling breast milk

• Wash your hands well with soap and water or use an alcohol-based hand sanitiser containing at least 60% alcohol.
• Inspect the pump kit and tubing to ensure cleanliness, and replace mouldy tubing immediately if using a shared pump. Clean pump dials, power switch, and countertop with a disinfectant wipe if using a shared pump.

2. Storing breast milk after expressing

• Use breast milk storage bags or clean, food-grade containers made of glass or plastic with tight-fitting lids. Avoid containers with the recycle symbol number 7, indicating BPA-containing plastic.
• Do not store breast milk in disposable bottle liners or plastic bags not intended for storing breast milk.
• Freshly expressed milk can be stored at room temperature (77°F or colder) for up to 4 hours, in the refrigerator for up to 4 days, and in the freezer for about 6 months (best) or up to 12 months (acceptable). Clearly label the breast milk with the date it was expressed.

3. When freezing breast milk

• Store small amounts (2 to 4 ounces or the amount offered at one feeding) to prevent waste during thawing.
• Leave about one inch of space at the top of the container to accommodate expansion during freezing.
• If delivering breast milk to a child care provider, label the container with the child’s name and follow any other specific requirements for labelling and storing breast milk.
• Breast milk can be stored in an insulated cooler with frozen ice packs for up to 24 hours while travelling.

4. Safe thawing of breast milk

• Always thaw the oldest breast milk first, following the first-in, first-out principle.
• Thaw breast milk using methods like the refrigerator overnight, warm/lukewarm water, or lukewarm running water.
• Never thaw or heat breast milk in a microwave, as it can destroy nutrients and create hot spots.

5. Feeding expressed breast milk

• Breast milk does not need to be warmed and can be served at room temperature or cold.
• If you choose to warm it, place the sealed container in a bowl of warm water or hold it under warm, running water (not hot) for a few minutes.
• Test the milk’s temperature before feeding by putting a few drops on your wrist, and avoid heating it directly on the stove or in the microwave.
• Swirl the breast milk to mix the fat, which may have separated.
• Use leftover milk within 2 hours if your baby does not finish the bottle.

6. Safe cleaning of infant feeding items and pumping equipment

• Carefully clean, sanitise, and store pump equipment, baby bottles, and other feeding items to protect breast milk from contamination. Follow CDC guidance on safely cleaning and storing pump equipment and infant feeding items.

Remember to follow these guidelines to ensure the safe and effective storage, thawing, and feeding of breast milk for your baby’s health and well-being.

Now it’s time to break it down.

Best Practices in Storing Breast Milk

If you have low milk supply and you want to build a stash for your baby, or you’re a working mum and you want your baby to consume your breast milk while you’re away, it’s very important to know that pumping is half the battle. Storing your expressed milk properly is also crucial to be able to succeed in your goals. 

So, what are the things you need to remember when storing breast milk?

The most important thing to consider when pumping and storing breast milk is cleanliness. Milk is a biological substance full of probiotics and commensal bacteria.

It is, therefore, recommended that methods of frequent hand washing, using clean containers, minimising milk transfers, and pumping directly into storage containers are followed.

How to Label and Which Container to Use

Plastic milk bottles or glass containers are also acceptable, and no evidence supports one over the other. But if you plan to store your breast milk in the freezer, it’s best to invest in breast milk storage bags or clean food-grade containers with tight-fitting lids. Avoid plastic containers using bisphenol 7 A (BPA) (recycle symbol #7). 

Freeze milk in small amounts of 2 to 4 ounces to avoid wasting any. But as your baby grows, you can opt to store the milk in amounts appropriate for the baby. Another reminder: when freezing, leave an inch of space at the top of the container because breast milk expands as it freezes.

Label milk with the date it was expressed and the child’s name if delivering to childcare.

Travelling from work to the house? Milk can be stored in an insulated cooler bag with frozen ice packs for up to 24 hours when you are travelling.

Where Is the Best Place to Store Breast Milk

Experts agree that the milk bags should be stored in the back of the freezer or refrigerator, not the door to ensure optimum quality or keep it as cold as possible.

Why does breast milk need to be cold?

Milk has a feature that leads it to maintain its nutrient value. It also discourages the growth of bacteria when kept at room temperature or in the refrigerator.

After four hours at room temperature or four days in the refrigerator, it may be best to freeze milk for long-term usage. Within 6 months is best, but it is still safe for the baby’s consumption at 12 months or less. 

Can You Store Breast Milk in the Fridge or Freezer With Food

Here’s what Yvon says:

“You can store your breast milk in the chiller, right at the back of the refrigerator, if you intend to feed the milk within the next 2 to 3 days. Simply make space for your bottles, and set all uncooked, raw foods away from the bottles.

It’s only when you are working towards creating a stash before returning to work that you might want to consider an additional freezer. Otherwise, there isn’t a pressing need to!”

The new breast milk storage guidelines give mums who pump their milk a little more freedom when it comes to storage.

This not only leads to reduced loss of breast milk, but there is less stress on storage. If you are a pumping parent, this news will cheer you up!

Milk Pooling Now Allowed, As Per New Breast Milk Storage Guidelines

In the past, the guidelines recommended against combining breast milk with different temperatures or pooling it in one container. This led to inconvenience for mothers who had to prepare, clean, and transfer breast milk using multiple containers throughout the day, depending on their pumping frequency.

However, the updated recommendations on breast milk storage now state that mothers can mix warm and cold breast milk together, or even consider pooling milk over a 24-hour period. The AAP’s rationale behind this change is to minimise the waste of fat or calories that occurs each time breast milk is transferred to different containers.

The new guidelines from the American Academy of Pediatrics (AAP) state that milk pooling can be done throughout the day. To simplify, this would mean that as mothers pump their milk, they can add an afternoon session to a morning session of pumped milk. So, when breast milk is used later in the day, the composition will become more nutritious.

This is because breast milk’s nutritional value changes over the day.

Several resources claim milk pooling cannot be done with chilled and freshly pumped breast milk. This may give rise to bacterial growth.

However, AAP notes that warm and cold milk can be mixed with the milk pumped in sessions within 24 hours. They can be combined without any problem. 

So that’s more storage space in the freezer and less bottles to clean for us too!

Thawing Breast Milk

Now that you already know proper breast milk storage, the next step is learning how to properly thaw it for your baby. This step is also crucial as the wrong practice can cause your child to drink breast milk that is already bad.

Always thaw the oldest milk first. Thaw milk under lukewarm running water, in a container of lukewarm water, or overnight in the refrigerator.

Never thaw or heat milk in a microwave as doing so will affect the composition of your breast milk (the microwave destroys nutrients) and creates hot spots, which can burn your baby’s mouth.

How Long Can Thawed Breast Milk Be Kept at Room Temperature

Once you’ve thawed breast milk, it should be consumed as soon as possible. Once you remove it from the freezer, you have a couple of hours to feed it to your baby if it’s at room temperature, and up to 24 hours if it’s kept in the refrigerator. 

If you know you’ll be out and about and won’t be able to use your pumped milk in time, consider using a cooler to keep it cold while travelling or transporting it back home.

You cannot re-freeze thawed milk so if you missed the safe window, err on the side of caution and discard it right away.

Why Is There a Weird Taste? Does It Mean That It’s Already Bad

“Is it normal for thawed breastmilk to taste metallic with a spit-up smell? My baby did not reject the milk.”

According to Yvon Bock, an International Board Certified Lactation Consultant (IBCLC) and founder & CEO of Hegen Pte Ltd, Singapore’s leading mother and baby care brand, it is perfectly normal for milk to have a certain change of taste when stored in the fridge.

“It’s normal due to the lipase properties in the breastmilk. It brings no harm and there is no intervention needed if your baby did not reject the milk,” she said.

Human milk contains lipases that may break down triglycerides, even frozen milk. These fatty acids can give the milk an unpalatable taste. While it won’t cause additional bacterial growth or altered nutrition, some babies may reject the taste of the milk. 

Keeping the milk colder may help to slow down the process. While heating may alter some of the biological makeup of the milk, it is better than your baby rejecting the milk due to taste alone. 

Here’s a quick guide from CDC on proper breast milk storage:

Feeding It and Giving It to Baby

Breast milk can be given to a baby cold, at room temperature, or warm. It all depends on your bub’s preference.

To heat milk, place the sealed container into a bowl of warm water or hold under warm running water. You may use those bottle warmers being sold, but remember that it’s a big no-no to heat breast milk in the microwave.

Always test the temperature before feeding it to your baby by putting a few drops on your wrist. It should feel warm, not hot.
Swirl the milk to mix the fat, which may have separated. If your baby did not finish the bottle, leftover milk should be used within 2 hours or discarded if it’s past that time.

Signs that Breast Milk is Already Bad

Breast milk is a precious and essential source of nutrition for infants, but it is crucial to ensure that it remains safe and fresh for the baby’s consumption.

As stored breast milk can undergo changes over time, it is important for breastfeeding mothers to be aware of the signs that indicate breast milk may have gone bad. These signs can help prevent feeding compromised milk to the baby and avoid potential health risks:

1. Unusual Odour: Breast milk that has gone bad may have a sour or rancid smell.

2. Off Taste: Bad breast milk might taste different than usual, often described as sour or soapy.

3. Separation: If the breast milk appears to have separated into layers, with a watery layer on top and a thicker layer below, it may be spoiled.

4. Clumps or Lumps: Clumps or lumps in breast milk can be a sign of spoilage.

5. Discolouration: Changes in colour, such as yellowish or brownish tints, may indicate that the breast milk is no longer fresh.

6. Curding: Breast milk that curdles or forms chunks when poured into a container might be spoiled.

7. Unusual Consistency: If the breast milk becomes unusually thick or slimy, it may have gone bad.

8. Excessive Bubbling: Excessive bubbling or foaming when shaking the breast milk may suggest spoilage.

9. Unsettling in the Freezer: If breast milk separates into distinct layers or looks grainy after being thawed from the freezer, it could be bad.

10. Baby’s Refusal to Drink: If a baby refuses to drink breast milk that they usually consume eagerly, it could be an indication that the milk has spoiled.

If unsure whether your breast milk is already spoiled, it’s best to err on the side of caution and just discard it. And that is why it’s essential to handle, store, and use breast milk properly to ensure its safety for the baby’s consumption.

How to Clean Breast Pumps and Milk Containers

Proper washing and sterilising of the breast pumps and milk containers will prevent the breast milk from being contaminated so this step, despite being so mundane, is also important. KK Women’s and Children’s Hospital recommends to mums in Singapore this guideline for breast milk storage:

• Wash all parts of the breast pump that come into contact with your breast milk in soapy water and rinse thoroughly.
• Sterilise using the steaming, boiling or chemical-soaking method.

Steaming

• Follow the manufacturer’s instructions.

Boiling

• Submerge washed expressing kits in a container of clean water. Cover the container and allow the water to boil.
• Let the water boil for another 10 minutes.
• Allow the water to cool after boiling and discard from the container.
• Leave the sterilised kits covered in the container.

Chemical soaking method

• Use a plastic container with a lid that can hold all the expressing kits.
• Follow the manufacturer’s instructions on the use of a sterilising agent and prepare the solution.
• Submerge and soak washed expressing kits for at least an hour.
• Change the solution every day.
• Store all expressing kits in a clean and dry container until your next expression.
• Wash your hands with soap and water before picking up the sterilised items.

If you have any questions about breast milk storage, do not hesitate to reach out to a lactation counsellor or a breastfeeding expert in a nearby hospital. 

Updated by Pheona Ilagan

Here at theAsianparent Singapore, it’s important for us to give information that is correct, significant, and timely. But this doesn’t serve as an alternative for medical advice or medical treatment. theAsianparent Singapore is not responsible for those that would choose to drink medicines based on information from our website. If you have any doubts, we recommend consulting your doctor for clearer information.