How to Store Breast Milk in Fridge

Storing expressed breast milk correctly, whether you’re expressing to return to work, ease mastitis or build your breast milk supply, will limit how much of your breast milk is wasted.

If you’re spending a lot of time expressing to extract a few precious drops —like me— you know how much it can hurt to waste breast milk.

Storage Containers

You can use pretty much any container for storing breast milk on the bench, in the fridge, freezer or deep freeze as long as it has a lid.

In most cases the container doesn’t have to be sterilized, it does need to be washed and either dried with a paper towel or covered and left to air dry.

It’s important not to use a container that has been used to store fatty foods as sometimes traces of oil can be left behind, even after washing.

I found lidded ice cube trays really great for storing breast milk. Especially when I first started back at work and I wasn’t sure how much milk to leave for my baby.

Using ice cube trays made freezing breast milk easy. I could freeze it in small quantities and my mum could defrost it as my son wanted it…so that less was wasted.

The cheapest way to preserve breast milk – Ice Cube Trays

I learned this the very hard way as I got used to freezing breast milk in the bottle that I had expressed it into.

This cost me lots of money because I was always buying new bottles to use as breast milk storage containers. It wasted milk too as sometimes my son would take a few sips and decide he didn’t want anymore.

Once your baby starts a bottle whatever they don’t finish must be thrown away…so there went 120mls of my precious breast milk -which at that stage was taking me ages to express.

That’s when I started storing breast milk in ice cube trays. I’d freeze a whole tray worth of breast milk and I’d put the separate cubes into another container to take to my mom’s. From there she would put the frozen breast milk into my son’s bottle, defrosting one or two cubes at a time.

There are also disposable breast milk storage bags you can get which will clip into the teat of your baby’s bottle. These are also a great alternative to freezing breast milk in bottles or containers as you don’t need to handle the breast milk at all.

It goes from pump, to bag and from bag to baby. They can be frozen and the breast milk can be defrosted under the tap or in the fridge overnight.

How long does it keep?

Freshly expressed breast milk can last on the bench for 6-8 hours, in the back of the fridge for 3-5 days, in the freezer for 3 months, and in the deep freeze for 6 months.

Frozen milk that has been thawed in the fridge can last 24 hours if kept in the fridge or 4 hours max at room temperature. Once defrosted, expressed breast milk cannot be refrozen.

If you take a look at your frozen breast milk and it looks layered, chances are it’s all good and there’s nothing to worry about. Expressed breast milk separates into several layers and it also freezes in layers.

And, if once thawed or warmed it looks like it has white flakes in it, this is generally also normal and the milk should be perfectly fine for your baby to drink.

Warming breast milk from the fridge

To warm frozen or cold breast milk you can run it under cold running water and then gradually increase the temperature of the water as you go.

Give it a good shake if it’s frozen and you will see how easily and quickly it breaks up and defrosts. It’s not as solid as frozen water so it warms up quite quickly…this is some consolation for hubby or grandparents when they have a hungry screaming baby.

It’s best not to use boiling water to warm breast milk and do not put it in the microwave as this will kill the nutrients in it.

My parents and my in-laws shared the babysitting when I went back to work and my in-laws were convinced that my frozen breast milk was not healthy for my son to drink.

To avoid the usual lecture I got when I dropped him off in the morning, I would put my frozen cubed breast milk into a bottle and let it defrost in the fridge overnight.

I would assure them that it was freshly expressed and at the same time I’d tell them which bottles to use up first…knowing that once thawed my breast milk couldn’t be refrozen.

Can warmed breast milk be refrigerated again?

If the breast milk has been warmed, but your baby didn’t drink it, you don’t have to throw it away if it hasn’t been in contact with the bacteria in the baby’s mouth. It can be stored in the refrigerator for 4 more hours. Use it at the next drink, otherwise, it will have to be thrown away.

Mixing milk from different days

If you are like me and are expressing a few mils at a time, and wonder whether you can mix breast milk from different days you’ll be glad to know that you don’t have to have 101 5mil containers storing breast milk in your fridge or freezer.

You can add unfrozen breast milk to frozen breast milk. Just make sure it’s been in the fridge first so that you are adding cold milk to frozen milk. If you add room temperature milk to frozen milk the top layer of frozen milk may start to thaw and allow bacteria to grow.

The same goes for adding milk to cold milk. So if you have 10 mils sitting in the fridge and you just expressed another 10 mils, leave them in the fridge in separate containers for a while, until the newly expressed milk cools down…then you can add them together.

It’s also a good idea to label your breast milk storage containers so that you and your baby’s carer know which milk to use up first. And only fill your containers about a third of the way as breast milk expands when it freezes.

Final word

So even if you are expressing to relieve engorgement or mastitis and not even thinking about leaving your baby in care at this stage, storing breast milk in the fridge or freezer at home is a great way to make sure that you have milk to leave for your baby when you do.

Please always remember to consult your health professional to find out information that is relevant to your specific situation.


Proper Storage and Preparation of Breast Milk – CDC.

Breast milk storage: Do’s and don’ts – Mayo Clinic.

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