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HealthInfo Waitaha Canterbury

Storing & using breast milk

Store expressed breast milk in plastic or glass containers with airtight, sealed lids. Use BPA‑free plastic wherever possible. Label each bottle or container with the date and time. If you're taking the milk outside your home, write your baby's full name on the label too.

Store milk in amounts from around 60 ml to 200 ml, making sure there is some empty space at the top of the bottle. Milk expands when freezing and if the bottle is full, it will spill over the top.

If you're planning to express a few times a day and you're getting small amounts each time, you can put the expressed milk at the back of the fridge. When next expressing, also put the new milk in the fridge. When the second bottle of milk has cooled to fridge temperature, you can mix the two bottles. You can do this for any milk you express within 24 hours as long as you always cool the new milk before adding it.

Never add warm milk to cold milk or to frozen milk. This can cause part of the milk to thaw and may lead to bacterial contamination.

Store expressed breast milk at the back of the fridge. Fridge doors tend to get opened a lot and the back of the fridge is cooler.

If you cannot store expressed milk in the fridge or freezer straight away, put it in a chilly bin with ice packs in contact with the bottles. Keep it no longer than 24 hours.

Breast milk storage guidelines for well and healthy full-term babies at home

Storage conditions

Storage time

Handy hints

In a room (< 26ºC)

4 hours

Cover the breast milk and keep in the coolest place possible.

In the fridge

3 days

Store milk at the back of the fridge.


  • Freezer box in fridge
  • Separate fridge/freezer
  • Deep chest freezer


  • 2 weeks
  • 3 to 6 months
  • 6 to 12 months


Use the frozen breast milk to mix with your baby's food when you introduce this from 6 months.

Some plastic feeding bottles are better for a baby's health than others. Avoid any clear, hard, plastic bottles or plastic containers without a number on the bottom of the bottle. Avoid containers with the numbers 3, 6 and 7. BPA‑free bottles are available.

Using stored breast milk

Thaw frozen breast milk slowly in the fridge. If you need to thaw it quickly, put the bottle of milk in warm water.

Never use a microwave to thaw or heat breast milk. This can cause uneven heating, which can scald a baby's mouth. It also damages some of proteins that pass immunity to your pēpi (baby).

Warm the expressed breast milk in a jug of hot water. Test the temperature of the milk by shaking a few drops onto the inside of your wrist.

Do not re-warm breast milk that has been defrosted and previously heated.

Breast milk can vary in colour and doesn't look like cow's milk or formula milk. It can be yellowish, bluish or quite pale and watery looking. All these colours are normal. Sometimes the fat separates during storage and goes to the top of the milk. If this happens, shake the bottle gently before using the milk to mix the fat back in again.

Written by HealthInfo clinical advisers. Page created December 2021.


See also:

Expressing milk & using breast pumps

Page reference: 928237

Review key: HIBRF-24381