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The do's and don'ts of breast milk storage

Bella Heim

Bella Heim

Bella is a mummy of three, writer, and photographer. She's not afraid to admit that she relies on a little red wine to keep the chaos of motherhood at bay. When she's not dodging toys and dirty diapers, you'll find her documenting the wild and wonderful ride of parenthood, and adding a splash of inspiration, creativity, and a healthy dose of mum humour along the way.
Created on Jan 22, 2024 · 8 mins read

When I decided to breastfeed my baby, I had no idea I was signing up for a 101 on how to run a dairy farm (but perhaps running an actual 'cow' dairy farm would have been easier).

Because for those long months, I played multiple roles: I was the manager, responsible for hygiene and breast milk storage; the milkmaid, handing the breast pump, the dairy hand who labelled stored milk, the quality control inspector, and most importantly (and humbling), the cow.

And while running my baby’s personal dairy plant was exhausting, it got easier once I understood the do’s and don’ts of breast milk storage.

Understanding breast milk and storing it

Breastfeeding provides your baby with all the necessary nutrients for growth and development, giving them those essential fatty acids. It also helps to strengthen the bond between you two. But it can come with its own set of challenges – especially when it comes to storing breast milk.

In 1854, O.H. Needham invented manual pumps, which paved the way for better milk-expressing equipment and other feeding equipment that allowed women to express and store breast milk.

Today, with breastfeeding medicine, electric pumps, insulated containers and ice packs, pumping, storing and preparing expressed breastmilk has become easy.

And yet, one study found that 96% of babies were breastfed soon after birth, but only 15% were breastfeeding at the five month mark. One of the reasons many mums give up on breast milk? Cracked nipples and poor attachment.

Expressing and ensuring proper storage can help many mums continue with their breastfeeding journey.

The do's and don'ts of storing breastmilk

It’s crucial to store breast milk properly if you want to avoid any ‘spoiled milk’ drama. You want to hold onto the nutritional value and immune health qualities of expressed milk, so your little one gets all the goods and none of the harmful bacteria. After-all, freshly expressed breast milk is too good to be wasted.

1. Do store breastmilk in a clean bottle/ breast milk storage bag

When it comes to storing expressed breast milk, always make sure to use a clean container or bottle that is food-grade and BPA-free.

Ensure you give it a good wash with hot soapy water and sterilise with tablets or a UV sanitising machine.

Pro-tip for the Dairy Farmer: breast milk storage bags are the best way to go for storing expressed breast milk, especially if you like to build a stash for later use. They stand upright for easy filling, can be stored flat, and take up less space. Plus, they don’t require sterilization and are way easier than plastic bottles.

Keep in mind, these storage bags are a one-time use kind of deal. Don’t be cheap and attempt to reuse them because you risk contamination and leaks. These bags are made of a special material that can withstand freezing and thawing without leaking (like a cooler bag), but they’re not indestructible; they can easily be punctured or torn.

So go easy on them, because its no use crying over spilt milk. Literally.

Remember to follow the manufacturer’s instructions, because different brands may have different guidelines for storing milk.

Another option is breastmilk storage containers. They’re more durable than plastic containers and keep freshly expressed milk safe and clean.

2. Do label your breast milk with date and time

When it comes to storing freshly expressed breastmilk, label it with the date and time it was pumped. You don’t want your baby chugging expired milk, as it can become contaminated with harmful bacteria (be sure to discard the oldest milk containers that are past the storage limit).

Another reason is the milk itself! (I always get fascinated by how yellow my early milk looked!)

Labelling the time when the expressed breast milk was pumped is useful because freshly expressed breast milk can change throughout the day and adjust to what your baby needs at that specific time. That way, you can thaw and feed the day-time expressed milk during the day.

Free Grayscale Photo of a Mother Breastfeeding Her Child Stock Photo
3. Do store breast milk in the back of the fridge or freezer

Is it fresh? Is it not? The petals of an ox-eye daisy may not have the answer to your questions. That’s why you should store breast milk in the back of the fridge or freezer.

It’s the coldest spot in the house! And we know that the colder, the better when it comes to keeping breast milk fresh and safe for your little one.

Remember, breast milk that was freshly expressed into a clean container can be stored in the refrigerator (up to 5°C) for 4 days—in the back!

Anything above 72 hours, and it needs to go.

The freezer, of course, buys you a bit more time: About 6 months is best; up to 12 months is acceptable.

4. Do NOT leave breastmilk out at room temperature for too long

The secret to running a successful dairy farm? Timing.

Leaving breast milk out at room temperature for too long is a recipe for disaster, with bacteria taking over and making your little one sick. So, here’s the deal: expressed milk can hang out at room temperature (77°F or colder) for up to 4 hours, then it’s time to transfer it to the fridge or freezer.

Freezing breast milk holds onto the freshness and nutritional value of breast milk for up to six months meaning you can have a steady backlog.

5. Do NOT reheat breast milk more than once

So the baby changed its mind and decided it wasn’t hungry! Can you reheat the breastmilk and still salvage that precious white gold?

Actually, no!

Reheating breast milk more than once can cause the nutrients to degrade and that’s not something you want. Think of it like a leftover pizza….except pizza isn’t nutritious, so okay, maybe not pizza. But you get the point.

The same goes for frozen milk, it’s best to use it within a couple of hours of taking it out of the fridge or thawing it from the freezer. Freezing breast milk is so helpful for mums, so you don’t have to avoid it. Just make sure you do it mindfully.

If you’re confused, here’s a table to to help out:


Information taken from: healthdirect.gov.au

Next time you want to warm up your breast milk, be sure to use it all within a couple of hours.

6. Do NOT mix freshly expressed breast milk with refrigerated or frozen breast milk

Mix-and-match may work well with your wardrobe, but it could cause havoc with breast milk.

Mixing fresh breast milk with refrigerated or frozen breast milk causes the temperature of the milk to change, affecting its quality.

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Store expressed breast milk - FAQ's

1. How long can you store breast milk?

Storing breast milk at room temperature? You’ve got 4 hours to either feed it to your baby or find a nice little cold spot for it in the fridge or freezer. Thawed breast milk is best when used immediately. In the fridge, expressed milk stays good for up to 4 days, and frozen milk can be stored for up to 6 months.

For any extra information on storage guidelines and how to safely store expressed breast milk, you can access infant feeding guidelines from the Australian government here.

2. How to thaw frozen breast milk?

Thaw breast milk by warming it up with a warm bowl of water or thawing it slowly in the fridge.

Place the expressed breast milk bag in a bowl of warm water and gently swirl. Dash in some hot water until the frozen milk becomes liquid, then transfer it to a clean feeding container where the milk can be stored.

Free Crop faceless mother in casual clothes embracing and feeding cute newborn baby with milk from bottle in daylight at home Stock Photo

3. Can warmed breast milk be refrigerated again?

Thawed milk can be stored at room temperature (26ºC or lower) until the end of the feed, in the fridge for 4 hours or until the next feed.

4. What if I have trouble expressing?

If breastfeeding is proving to be a tricky journey for you, it’s okay. Reach out to a lactation consultant to find support for expressing breastmilk.

A lactation consultant can provide practical tips and support, and give you that little helping hand. There are a lot of women struggling with expressing breastmilk, so you’re not alone. There are resources available, from techniques like hand expressing to expressing equipment and breastfeeding medicine.

Maintaining cleanliness

Breastfeeding is already a tiring job, and storing breast milk can be just one more thing to think about when you’re already juggling hormones, a healing body, sleep deprivation and the constant adrenaline rush of caring for a tiny human.

By ensuring that your little one is getting the best quality milk, you can rest assured that your baby will be healthy and happy.

From cleaning and labelling to storing and reheating, it’s important to take the necessary precautions to keep your freshly expressed breast milk safe and of top-notch quality. There’s no shortcut when it comes to sterilising breast pumps, containers, bottles and even when storing breastmilk.

That amazing expressed breast milk is a precious gift, and it’s so important to take good care of it—and yourself!

Wrapping it up

Running your baby’s personalised dairy farm, aka breastfeeding, is exhausting and stressful, but it is also one of the most amazing and rewarding jobs.

Also, did you know that the hours you spend feeding your child around the clock are equal to a full-time job?

Time for a promotion and a pay rise, methinks!








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