What's the best way to store breastmilk?

You can store your breastmilk to keep it fresh for your baby in a number of ways:

  • At room temperature (no more than 25 degrees C), for up to six hours.
  • In a cool box, with ice packs, for up to 24 hours.
  • In a fridge (at four degrees C or colder), for up to five days. Store it at the back of the fridge, where it's coldest, away from meat, eggs, or uncooked foods.
  • In a fridge’s freezer compartment, for two weeks.
  • In a home freezer (at minus 18 degrees C or lower), for up to six months.

If you're returning to work, try to get into the routine of expressing and storing your breastmilk. This will keep your milk supply up, and your baby can continue to get the benefits of your milk, even when you're not with him.

How you store your breastmilk depends on how soon you want to use it. If you plan to use it within a few days, refrigerating is better than freezing. Freezing destroys some of the substances in your milk that fight infection. Frozen breastmilk is still a healthier choice for your baby than formula, though.

Whether you choose to refrigerate or freeze your milk, you should:

  • Use sterilized containers. Opt for plastic bottles or plastic breastmilk bags. Glass bottles may crack or chip.
  • Label and date your bottles and bags, and use up the oldest ones first.
  • Keep your breast pump clean. Wash the parts in hot, soapy water, and rinse them thoroughly before sterilizing.
  • Wash your hands before expressing and handling breastmilk for storage. Keeping everything as clean as possible will make it less likely that bacteria will grow in your stored milk.

You can add freshly expressed milk to breastmilk that's already in the fridge, provided it has been expressed on the same day. Bear in mind, though, that you can only keep it until the original milk is five days old.

If your milk has been stored for some time, you may notice that it separates. This is normal, so just give it a gentle shake to mix it up again. Some babies will happily drink cold milk straight from the fridge, while others like it warmed up. You can warm the milk by placing the sealed bottle or bag in a bowl of warm water.

If you want to freeze your milk, do it as soon after expressing as possible. Leave a gap at the top of each bottle or bag, as your milk will expand during freezing. If you’re storing milk in bags, watch out for any tears. You may not notice any until you start to thaw the milk. Remember that plastic bags tend to fall over when thawing.

You could freeze very small amounts of milk in an ice cube tray, ideally one with a lid, or you could store the tray inside a sealed freezer bag. These smaller quantities defrost quickly and are ideal if you need some breastmilk to mix with your baby's food when you introduce solids.

You can add freshly expressed milk to frozen milk, as long as the fresh milk is chilled for at least an hour first. Make sure the amount you're freezing is smaller than the frozen portion.

Frozen breastmilk should ideally be defrosted in the fridge, and can be stored there for 12 hours. Never re-freeze breastmilk once it has thawed.

Don’t be tempted to defrost or warm your breastmilk in a microwave. If you need the milk in a hurry, defrost it under cool, then warm, running water, or place it in a bowl of warm water. Dry the outside of the container before you open it, and use it straight away.

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