How to Freeze Breast Milk Safely and Easily

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As a pumping mama, whether exclusively or just for fun (kidding), you are probably thinking about how to freeze your breast milk in order to create a freezer stash. While building a freezer stash isn’t absolutely necessary, there are some definite benefits to having one.

A freezer stash is great for emergencies where your supply drops, if you have to take a medication that isn’t safe for baby, and the primary reason is to be able to stop pumping sooner and still be able to reach your breastfeeding goal. Sounds good right?

If you’re going to start freezing breast milk, there are a few things that you should know first to help you maximize your stash while minimize your work.

(This post contains affiliate links. That means that if you buy something through one of my links I’ll receive a small commission at no extra cost to you. I will never suggest a product or service that I don’t use and love myself because that’s just wrong. If you like reading legal mumbo-jumbo then you can check out my disclosure policy HERE.)

Guidelines for Freezing Breast Milk

The Center for Disease Control (CDC) has some breast milk storage guidelines that are a really great baseline. (You can check it out HERE)

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My lactation consultant also always told me to follow the rule of 6’s.

  • 6 hours at room temp
  • 6 days in the refrigerator
  • 6 months in the freezer
  • up to a year in the deep freezer

These rules are for fresh milk. When handling previously frozen breast milk, the rules change slightly.

  • 1-2 hours at room temp
  • 24 hours in the refrigerator
  • NEVER to be refrozen

We’re talking about food that you’re going to give to your baby. You want it to be the best and healthiest that it can be.

That being said, that liquid gold is precious and if you’re smart about it you don’t have to risk wasting it.

How Do You Freeze Breast Milk?

The actual process of freezing breast milk isn’t actually that difficult. There are some things that you should take into account though.

Make Sure Things are Clean

Food for baby, remember? Make sure that your hands and any container that is going to come into contact with the milk is clean and preferably sanitized.

This will help to eliminate any bacteria that may try to form that could get your baby sick.

Thankfully too, breast milk is amazingly antibacterial. It takes a long time for any bacteria to grow in it and most bacteria can’t. That’s why it can sit out at room temperature for so long.

When your baby gets a little older and if he isn’t immunodeficient, you can relax slightly on some of strict standards. Like sanitizing.

I can’t actually remember the last time I technically “sanitized” my bottles. I do always wash everything in really hot, soapy water though.

My son is also a healthy, full-term baby that is almost 1 so I’m a little calmer about it.

If you aren’t comfortable with that (which I completely understand), then you can boil your pump parts and bottle parts to fully sanitize them. The CDC suggests doing this daily.

If you don’t want to go through all of that work every single day (who has that kind of time?), definitely get some of the Medela Quick Clean Steamer Bags. Those things are amazing.

Just pop your parts in the bag with a little water and microwave for a quick sanitize cycle. Definitely worth it.

Freeze Effectively

There are several options out there for freezing breast milk.

Freezing in your pumping bottles are a great option to minimize clean up and you risk spilling any by transferring to new containers. The downside is that they take up a large amount of room in the freezer and it will give you less bottles to pump into.

If you have a large oversupply, using those bottles will not be your friend.

I would suggest going and picking up some milk storage bags. I really like the Lansinoh storage bags ones myself, but there are others out there.

These bags are specifically made to hold breast milk. I know it sounds like a useless parenting trick to make you spend more money, but they really are great.

They’re meant to be leak-proof and they come pre-sanitized so you know that your milk will be safe to feed. The downside is that they are a 1 time use item. That cost can add up. I’d suggest buying in bulk if you know you’re going to use them.

Most bags will hold a maximum amount of 6 ounces. Even if your little one is not eating 6 ounces at a time now, that’s not to say that he won’t in the future. To save on space and money for bags, go ahead and freeze 6 ounces at a time.

Once you have your bag filled, lay it down flat in the freezer. I like to use a box or a pan for this. Just something that will allow it to be as flat as possible.

Once you have 10 of these you can make a “brick”.

Take a gallon sized storage bag (I like Ziploc), and put them in there vertically and alternating (up, down, up, down, etc.) You should be able to fit 9 in the bag and then you can lay 1 on top. Now you have 60 ounces in one nice, clean, storage compartment.

Always write the dates on the outside of the bag so that you know that you are rotating through correctly.

You always want to use the oldest milk first because the longer it is in the freezer, the more nutrients it loses. You also don’t want to risk missing a bag and it going past its expiration before you realize it. Organization is key here.

Can You Mix Breast Milk from Different Days?

Yes, but there’s a catch.

·         Adding Fresh Breast Milk from Different Days

If you have fresh milk from Monday that you want to mix with fresh milk from Tuesday to freeze, then you should make sure that the temperature of both containers of milk is the same. Refrigerated is best.

Then the milk will need to be dated for the oldest date since that is the oldest date of any milk in the mixture.

If you want to mix frozen milk and fresh milk, that can be done as well.

·         Adding Fresh Milk to Already Frozen Milk

Make sure that the fresh milk is completely cooled first before mixing with the frozen breast milk.

If the milk is freshly pumped and warm, then it will begin defrosting the frozen milk which can lead to bacterial growth and puts your baby at risk.

Once the fresh breast milk is cooled completely, then it can be added to the frozen milk and then frozen.

Do not defrost the frozen milk first!

·         Adding Defrosted Milk to Fresh Milk

It is perfectly fine to add previously frozen breast milk with freshly pumped milk. To be honest, you may have to do this the first few times you try to get your baby to drink the frozen milk.

It has a different flavor that not all babies immediately love. My son also spit up a good bit of his first couple of frozen bottles.

Mixing the frozen breast milk with some fresh milk really helped the problem.

Just keep in mind that once frozen milk is introduced to the mixture, then it must abide by the frozen milk guidelines.

Meaning that it cannot be left out at room temperature for nearly as long and it is only good for 24 hours once it is defrosted.

Because of this, I would strongly suggest just mixing as you need it rather than mixing your frozen breast milk and fresh breast milk in large batches.

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Thawing Frozen Breast Milk

The easiest way to thaw your frozen breast milk is to take out what you need the day before and let it defrost in the refrigerator overnight.

When you’re defrosting frozen milk, always, always, ALWAYS put the bag in a clean container first. I like to use a glass measuring cup myself.

This way, if the bag has a hole in it your precious breast milk isn’t wasted all over the bottom of your fridge.

I have done this and it was AWFUL! I wasted about 4 ounces before I realized it. It was so upsetting.

Another tip for thawing frozen milk is to have the bag in the container upside down. If the bag does have a leak, it is more likely to be on the bottom of the bag rather than the top.

I just recently heard about that suggestion and I can’t believe I didn’t think about it before! So smart.

If Your Baby Won’t Take Frozen Milk

When trying to get your baby to drink your frozen milk for the first time, he may not like it. I would definitely suggest trying this BEFORE you have several hundred ounces in the freezer.

Some women have an excess of liapse in their milk. There’s nothing wrong with it, it’s totally normal and not harmful to your baby. Some babies just don’t like the taste after it’s frozen.

You’ll be able to tell if you have high liapse if your previously frozen milk smells soapy or metallic.

Offer the milk to your baby first, if they don’t like it then you have a couple of options.

  • You can scald your milk before freezing it. Scald, not boil. This will help to burn off some of the excess liapse.
  • You can add a couple of drops of alcohol free vanilla to the milk before feeding.

Since I’m super lazy, I would rather use the vanilla. Since it’s going to be fed to a baby, I like THIS organic, sugar free vanilla extract. One drop for each ounce of milk should be enough though you can go up to 2 drops per ounce if need be.

I have also heard that high liapse milk typically smells and tastes the most “off” after it has been sitting out for a while.

What I mean is, if you know that you have high liapse, then if you can, freeze your milk either immediately after pumping or at least the same day.

Milk that sits longer in the fridge will start to develop different tastes and smells. Those differences are only intensified after the milk is frozen.

So if you have a picky baby, freeze the freshest milk possible.

Personally, I always make up two bottles at the end of the day for the next day’s feedings. Then I will freeze any leftover in 6 ounce increments.

I’ll have a couple of bottles to start the day, then I’ll just feed my son whatever freshly pumped stuff I make throughout the rest of the day. My milk never sits in the fridge longer than a day or two if I can help it.

Not everyone does this. I know some women that will leave milk in the fridge for several days before freezing.

My thought on that is this, freezing breast milk that has been sitting in the fridge for five days does not make it last longer. It’s still five day old milk when I defrost it. Food for baby, remember?

For more information on how to tell if breast milk has gone bad, check out this guide from Mom Loves Best. 

Donating Breast Milk

If you have a large oversupply and don’t have extra room for a deep freezer, or if you just want to help out a fellow mother, please consider donating some of your milk.

While milk donation is not a requirement of women with an oversupply and you should in no way feel obligated to do so, being able to help another woman feed her baby when she is physically unable to can be so worthwhile.

If you would like to donate milk, or if you would just like some more information, Human Milk for Human Babies is a great place to start.

Freezing breast milk takes a little effort, but if having a frozen stash will give you some peace of mind and allow you to stop pumping sooner and still reach your breastfeeding goals, doesn’t that make it worth it? I certainly think so.

Have you started a freezer stash yet? Are you having trouble figuring out where to start? Leave me a comment below or join the conversation in our Facebook group.

Until next time!

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10 thoughts on “How to Freeze Breast Milk Safely and Easily”

    1. Thank you. Moms should definitely feel comfortable and confident when dealing with their breast milk. I’m glad I could help.

    1. I agree. I never had a large supply, but I really wish that I could have been able to donate. There are so many women that can benefit from it.

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