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How to Freeze Breast Milk Safely

If you’ve chosen to breastfeed your baby, I have no doubt that there will come a time when you wish to express and store your milk for future use. In which case, you need to know how to freeze breast milk safely, to ensure that your baby does not catch an upset stomach, or worse, from badly stored milk.


Before freezing

  • Pump your milk into sterile containers and wash your hands prior to pumping.
  • Do not overfill your storage containers as the milk will expand once frozen and could cause the container to split, and therefore leak when thawing.
  • Breast milk should be frozen as soon as possible after expressing to reduce the amount of time that bacteria can grow in it. However, if you wish to combine milk from more than one pumping session, you should refrigerate your milk straight after pumping.
  • Milk from different pumping sessions can be combined. To do so, you should cool both sets of milk separately in the fridge, and then combine them as soon as possible once they are at the same temperature and freeze.
  • Do not add freshly pumped milk, which is still warm, to cold milk, as this is more likely to encourage bacteria growth in the milk.


Breast milk storage containers

The first thing to consider when freezing your breast milk is what type of storage container you will be using. Here’s a brief guide to the most popular options.

Storage bags

Lansinoh Breast Milk Storage BagsMedela Pump & Save Breastmilk bagsTommee Tippee Breast Milk Storage Bags

Pros: Convenient, no sterilisation required, large storage capacity per bag, easy to store in the freezer as can be lay flat.

Cons: Bags can be prone to tearing during defrosting, environmental impact of non-reusable plastic bags.

Recommended storage bags: I’ve used these Lansinoh Breast Milk Storage Bags (£7.99 for 50 bags) over and over again and as long as you don’t overfill them and squeeze the air out of them before freezing, they don’t leak when defrosting.


Storage pots

Tommee Tippee Closer to Nature Breast Milk Storage PotsPhilips Avent Breast Milk Storage PotsMAM Breast Milk Storage Pots

Pros: Reusable, some can be attached directly to breast pumps, some can be attached directly to bottle teats, cheaper than bags if you intend to express a lot.

Cons: Need to be sterilised between uses.

Recommended storage pots: These Tommee Tippee Closer to Nature Milk Storage Pots only have a 60ml capacity, but I really liked how they slot onto the top of a bottle to be used when I used them with my Tommee Tippee Manual Breast Pump. If you require a bigger storage capacity, try the Philips Avent Reusable Breast Milk Storage Cups which hold up to 180ml.


Ice cube trays

Silicon Ice Cube Tray with Clip-On LidAnnabel Karmel NUK Food Cube TrayBaby Weaning Food Freezing Cubes Tray

Pros: Defrosts quickly, great for newborns who only need small volumes per feed, resusable, cheap to purchase.

Cons: Very small volume per cube, need to be sterilised between uses, difficult to protect from bacteria in the freezer, prone to spillage prior to freezing.

Recommended ice cube trays: I love this Silicon Baby Food Freezer Tray with Clip-On Lid by Weesprout. When using it for breast milk, you will need to place it onto a flat tray prior to filling it because it’s silicone so it is very flexible. Aside from this, it’s a great ice cube tray which will help with future weaning purée storage too.


Using your frozen breast milk

  • Your breast milk changes as your baby grows so it’s important to use the milk before your milk’s constitution changes too much. The major changes in your milk happen when your milk first changes from colostrum to normal milk, and then again once your baby starts to wean onto solid food. At these times, it’s important that you don’t stockpile too much frozen milk as the nutrients that your baby will need may not be the same in the future.
  • Use the oldest milk first and maximum freezer storage times should be as follows according to the website

Breast Milk Freezer Times


  • When defrosting milk frozen in storage bags, place the bag into a additional sterilised container in case the bag has split during freezing. Then if the milk leaks from the storage bag, you won’t have to waste the milk.
  • Defrost breast milk in the fridge if possible within the time needed for your baby’s feed. Depending on the volume of milk, this can take up to 12 hours. Defrosting slowly in the fridge results in less bacteria growing in the milk.
  • If you need the milk more quickly, then defrost it by running under cold water, gradually increasing the temperature and then placing into a bowl of warm water.
  • Only warm the milk to the minimum temperature that your baby will drink. This is to avoid heating your milk for a prolonged period of time, which can assist bacterial growth.
  • Feed to your baby within 1 hour of when they first start the bottle, and then throw any remaining milk away.
  • Do not refreeze defrosted breast milk.



It’s common sense…

Hopefully you’ve noticed a theme during this post – most of what I’ve written above is common sense and the same kind of rules you would follow if you were preparing food to store in the freezer. The main difference with breast milk for your baby is to ensure that you use sterile containers and do everything possible to eliminate the risk of introducing bacteria to your baby before or after freezing.


If you have any other questions on the storage and usage of breast milk, please comment below. If you like this article, please share with your friends and come back soon for more!


4 responses to “How to Freeze Breast Milk Safely

  1. Clare

    Thank you so much for the informative page – just what I was after. I’m very keen to continue breastfeeding my litle one, but was starting to find it a bit of a bind if I want to go out. I bought all the stuff for pumping and storing my milk, but had no idea what to do with it – you are a lifesaver!

    1. Caroline Post author

      Hi Clare,

      I’m really glad that you have found this useful. I remember feeling so overwhelmed when I started to express and bottle feed my son, and because it was an effort to pump and store that precious liquid each time, I didn’t want to waste a single drop!

      Good luck with your pumping journey, please ask away if you have any other questions or want some further advice on this topic, or you can also email me on if you don’t wish to post publicly.


  2. Lauren Kinghorn

    Hi Caroline, excellent article, thanks! You are so thorough. I never got around to expressing and freezing milk, even though I’ve been breastfeeding for the last 3 years. I was lucky in that I didn’t have to go back to work. I must admit that it was also because I was clueless. It all looks so simple now when I see the images of the freezer packets and ice cube trays, but it seemed so tricky back then. Thanks for making it look so easy. If I have another child I’d really like to donate milk, so will refer back to this page then.

    1. Caroline Post author

      Hi Lauren,

      Wow 3 years – what an achievement, congratulations!

      Expressing did feel like hard work at first, and I do think I would have struggled to express frequently with a newborn, however at 6 months old I managed to get us into a solid routine for expressing at the same time as feeding my son his bottle (whilst he was sat in his bouncy chair).

      Donation of milk is something which I also considered once my son was weaning onto his prescription formula and I realised I had over 3 litres of frozen breastmilk that would be wasted, however in the U.K. you must have made your first donation before your own child is 6 months old. Just something to bear in mind.

      Wishing you all the best if you do decide to have another child, we have now realised we are slightly crazy to be expecting again in just 3 months’ time!



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