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How to Store Expressed Breast Milk

Expressed breast milk in Lansinoh storage bags

Breast milk is the best possible food to help your baby develop and grow. It contains antibodies, live cells, and other substances to help protect your baby from infection and illness.

When you’re breastfeeding, it’s important to store your breast milk safely to keep your baby safe and ensure they’re getting all the nutrients they need. Follow our guide on how to store expressed milk and learn how to safely heat it, too.

Storing Expressed Breast Milk

Breast milk is suitable for storing due to its antibacterial properties, which help it to stay fresh and discourage the growth of bacteria.

When you’re expressing breast milk, it’s particularly important to store your expressed milk in the right type of container to avoid contamination.

How Long Can Breast Milk Stay Out?

If you’re storing breast milk at room temperature, it must be used within 4 hours – as after that the milk starts to lose its healthy properties. However, it isn’t always practical to use breast milk within this four-hour window, so your fridge or freezer could become your new best friend when it comes to pumped breast milk storage.

Storing Breast Milk in the Fridge

Breast milk should be stored in plastic bags or breast milk bottles as soon as it has been expressed. However, keep in mind to not add body temperature breast milk into already chilled expressed breast milk unless it’s a very small amount.

It is best to avoid storing the milk in the refrigerator door due to temperature control. Instead, it’s best to store it in the coldest part of the refrigerator, which is at the back of the shelf that is just above the vegetable compartment.

How Long Does Breast Milk Last in the Fridge?

When you’re expressing your milk to use at a later date, it’s important to refrigerate or cool it immediately to ensure it has the longest shelf life possible. The NHS states that when stored correctly, expressed milk will last for:

  • Up to eight days in the fridge at 4C or lower.
  • Up to three days in the fridge if it’s higher than 4C.
  • Two weeks in the ice compartment of a fridge.

How to Store Breast Milk in the Freezer?

Whether you’re refrigerating or freezing the breast milk, it should always be stored straight after the expression. Ensure to use a container or bag that it’s suitable to be used in the freezer such as our freezer-proof Lansinoh Breast Milk Storage Bottles.

It’s recommended to keep frozen breast milk in the middle of the freezer where the temperature is most consistent. The temperature on the sides can fluctuate and if milk partially thaws, it can’t be refrozen.

Containers or bags should also not be filled to the top – leave at least 2.5cm of space to allow the milk to expand as it freezes.

How Long Does Breast Milk Last in the Freezer?

Expressed breast milk can be stored in the freezer at -18C or lower for up to 12 months – however, it is best used within six months.

Generally, the earlier you consume the milk the better, as the longer it will stay frozen, the more nutrients it will lose. For optimal freezing condition, store it in the back of the freezer.

Breast Milk Storage Containers

Refrigerated or frozen milk should be stored in either sterilised hard-sided plastic or glass containers with well-fitting tops, sterilised BPA or BPS free containers, or breastmilk bags that are specifically designed for storing expressed milk, such as Lansinoh® Breast Milk Storage Bags.

It’s also important to mark the container with a date so you know how old it is and when to use it by.

Tips for Storing Breast Milk

  • Wash your hands before expressing.
  • Wash your express milk pumpand containers in hot, soapy water, rinse well, and allow to air-dry before use. Alternatively, you can wash and dry in a dishwasher.
  • As well as marking the date on the container, also include your baby’s name on the label if your baby attends nursery or a childminder to avoid the milk getting mixed up with another child’s.
  • If you’re pumpingand storing your breast milk at work, make sure you label it with your name to avoid it getting mistaken for regular milk!
  • If you’re travelling and need to take expressed milk with you, chilled breast milk can be carried in a cool bag with ice packs for up to 24 hours.
  • It’s best to store expressed breast milk in smaller quantities to avoid waste.

How to Warm Breast Milk?

Warming up breast milk needs to be done efficiently and carefully, especially if you are wanting to use frozen breast milk.

How to Defrost Breast Milk?

There are two good options for those looking to defrost breast milk:

  1. If your milk is frozen, you can easily defrost it in the fridge – just remember to use it within 24 hours after defrosting.
  2. Alternatively, thaw and heat breastmilk under warm, running water, or in a bowl with warm or hot water.

To preserve the nutrients in your milk, it’s important to not heat your breastmilk in a pan on the cooker. It’s also recommended to never heat your expressed milk in the microwave as it won’t heat the liquid evenly which could cause hot spots and hurt your baby.

How Long Does Breast Milk Last Once Defrosted?

If you’re planning on keeping your breast milk in the fridge until use, we’d recommend using it within 24 hours after defrosting. However, you can also keep it at room temperature once fully thawed – in which case it must be used within a maximum of two hours.  

How to Defrost Breast Milk Fast?

If you need to defrost your milk more quickly, hold the container under a cool running tap and gradually increase the temperature of the water to heat the milk to a safe feeding temperature. Alternatively, immerse the container in a bowl of warm water. If the water has become cold before the milk has defrosted, take the milk out and reheat the water if necessary.

Once you’ve heated your milk, gently swirl the milk before testing the temperature. Mixing will also redistribute the cream into the milk as stored milk will separate into a cream and milk layer. Avoid shaking vigorously as it could damage some of the live components of the milk.

Reheating Breast Milk

We only recommend heating breastmilk once when thawed using the tips provided above, we do not suggest refreezing once thawed.

How Much Milk Should I Express?

To ensure you’re not wasting any breastmilk, store your expressed milk in 60 to 120ml (2 to 4 oz) quantities, at least until you know how much milk your baby consumes at each feed.

If you think your baby may need more, you can also store in smaller quantities of 30ml and combine with larger measurements.

To combine milk pumped at different times, first cool your fresh milk for 30 minutes in the fridge, then add the fresh milk to the frozen batch (only if there is less fresh milk than frozen). When using a mixture of milks pumped at different time, also remember to use it by the shelf life of the oldest expressed milk.

Why Does My Breast Milk Have a Soapy or Rancid Smell?

In very rare cases, some mothers may find that their milk smells soapy or rancid after storing. This happens when a mother produces milk that is high in lipase, an enzyme that breaks down fat in the milk.

Depending on the level of lipase, some mothers notice this rancid smell after their milk has been stored in the refrigerator; others notice it only after the milk has been frozen for a while and then thawed. Thankfully, this doesn’t happen often and can be prevented if the lipase is detected before the milk is frozen.

We suggest mums expressing milk test freeze some batches and thaw them after about a week to be sure they haven’t spoiled. If it does smell rancid when thawed, the milk can be scalded before freezing in the future to deactivate the lipase. For more information, refer to this article published by La Leche League International.

Most importantly, don’t forget that help is available! If you have any questions about breastmilk storage, speak to your midwife, health visitor or doctor for support. Or for further reading around breast milk, check out our handy guides on the breast pumping basics and feeding expressed breast milk.

What’s more, you can follow us on our social media pages for even more great advice, hints, tips, and general conversation about all things parenting and breastfeeding. Join in the conversation on FacebookInstagram and YouTube.

Please note: the guidelines on this page are recommended for healthy full-term babies. For advice on expressing milk for a premature or ill baby, please visit the Bliss website here.

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