This is our handy guide for expressing mums on how to store your breast milk to keep it safe and fresh for baby. Breast milk storage is particularly important if baby will not receive milk for a few hours , days or weeks.
Storing Breast Milk Guide
What container should I use for storing breast milk?
If you will be feeding baby the same day it is recommended you pump and store into a glass or BPA free plastic bottle which can be closed with a capped lid. Once it comes to feeding baby then you simply swap the cap for a teat. This means minimal milk transfer to prevent contamination and means less bottle cleaning for mum.
If the baby will use the milk within a few days you can use a capped bottle again. However if space is tight in your fridge then you can pump straight into a storage bag such as the Lansinoh bags or the Medela pump and save . These are specially made for breast milk storage and can be laid flat and easily stacked.
If you are freezing the breast milk to build up a supply for future it is recommended to use specialist breast milk freezer storage bags or a breast milk freezer tray which separates the milk into 1oz portions.
- Do not use regular food storage boxes as these may not be BPA free (a controversial chemical which can be harmful to babies).
- Regular food storage bags may also leak and the plastic may interfere with the nutrients in the milk.
- Do not fill the container all the way to the top if freezing. The milk will expand, so it’s best to leave at least an inch free at the top.
- Try storing your milk in 1-4 oz portions so you can thaw the amount you baby is likely to eat in order to reduce waste.
How long can I store breast milk?
Freshly expressed breast milk can be stored safely in these conditions:
- Room temperature (19-26°C, 66-78°F) for 4-6 hours.
- Warm Room (27-32°C, 80-90°F) for 3-4 hours
- Cool box ( 15°C, 59°F) for 24 hours
Refrigerated Milk (stored at the back away from the door) can be stored safely for:
- Fresh milk (0-4°C, 32-39°F) for 3-8 days (ideally within 72hours)
- Thawed milk (0-4°C, 32-39°F) for 24 hours
Frozen Milk (stored at the back away from the door) can be stored safely in:
- Small freezer compartment in fridge for 2 weeks
- Freezer (<4°C, <39°F ) for 6 months
- Deep freeze (-18°C , 0°F) for 12 months
Remember to date all milk containers with waterproof labels and ink before storing . If you are in a shared storage facility such as a special care baby unit it is recommend you add your babies name to any storage container to avoid any mix ups.
What’s the best way to store milk?
Always allow milk to cool down to room temperature before storing within a fridge or freezer. When placing into the fridge or freezer choose a spot at the back and furthest away from the door, not in the door shelves. This prevents irregular temperature changes if the door is being opened often. You can also get a handy gadget called the Milky freeze which helps you to keep milk in use by order.
Does cooling/freezing breast milk destroy nutrients?
Ideally any stored milk should be used within a few hours or days to ensure it is fresh and nutritious. Studies have shown that the longer milk is refrigerated or frozen then it continues to lose vitamin C. There is also some evidence that increased storage times can affect the anti-bacterial properties and fat content of breast milk. Breast milk constantly changes to meet your babies nutritional needs, so milk expressed when the baby is 1 month old will not be nutritionally complete for your baby at 3 months old, but still better than formula.
How do I thaw frozen breast milk?
Thaw frozen milk in a refrigerator slowly over 12 hours. Don’t leave frozen milk at room temperature to thaw, the varying temperature changes make it more susceptible to bacteria growth. If you need the milk thawed quicker you can run the container under a cool running tap, slowly increasing to warm, or leave in a bowl of warm water.
Thawed frozen milk can be kept in the fridge for up to 24 hours. Do not refreeze thawed breast milk.
How do I re-heat breast milk?
Place the container in a bowl or jug of hot water for a minutes. Alternatively use a bottle warmer. Always test the milk on the back of your hand before feeding to baby, it should feel neither hot or cold.
Never heat a bottle of milk in a microwave or quickly on a stove. This creates heat pockets within the bottle leaving some parts boiling hot and other cold. These heat pockets can scald a baby’s mouth and leave serious injury. Rapid heating of milk can also destroy the anti-bacterial properties of the milk.
Can I mix fresh and frozen milk?
Yes you can mix the milk, however you must make sure the frozen milk is thawed through and the fresh milk is cooled in the refrigerator before mixing. Swirl the milk together to mix, don’t shake as this can affect the nutrient content of the milk. Never refreeze any leftover milk made up this way.
How will I know if the breast milk is ‘off’?
Frozen breast milk may appear slightly watery once thawed. Do not use the milk if it is past it’s ‘use by’ date, or if it smells really bad or tastes sour.
What about storing breast milk at work?
Although milk can be stored at room temperature for 6 hours, it is recommended that you take an ice packed cooler bag with you to store any containers with expressed milk. Although it is not a legal requirement, the Health and Safety executive recommend your employer provides you with equipment such as a fridge to store your expressed milk at work. To read more about the your breastfeeding rights when returning to work check out the HSE website.