Storing and using breast milk


Mother's milk is a living fluid; it contains many nutritional and protective components which are retained with normal good food handling techniques.

Safe storage guidelines aim to provide optimal preservation of the unique breast milk constituents, and prevent bacterial contamination.

Signs of milk transfer

  • Careful hand washing before pumping or expressing, use of clean and sterilised equipment, (see Cleaning and Sterilising Equipment below).

  • Collect colostrum, the first milk, by syringe. When more milk becomes available store in a sterile plastic container. At home use a sterilised jar with a screw on lid.

  • Label the container with the baby's name, hospital number, date and time of collection.

  • Protect breast milk from sunlight and phototherapy treatment

Storage times for fresh expressed breast milk

  • At room temperature studies have shown breast milk remains stable for up to 6 - 8 hours (25°C and lower) but it is best transferred to a cool place e.g. a refrigerator within 4 hours.

  • In a refrigerator may be stored up to 2 days (at 4°C or lower) but if not required immediately it should be frozen within 48 hours. 

  • Frozen breast milk may be stored for 2 weeks in a freezer box inside a refrigerator, 3 months in a front opening freezer for fridge/freezer, or 6 months in a chest freezer at a constant - 20°C. (Store towards the back of fridge or freezer - for coldest and more constant temperature.) 

  • Thawed milk stored in a refrigerator may be used for up to 24 hours, and then the remainder needs to be discarded. Thawed milk at room temperature - up to 4 hours.

  • Reheated milk should be used at once, for completion of the feed. Discard any unused milk that has been reheated.

  • If breast milk requires fortification, e.g. some premature infants, the breastmilk should be used immediately if possible, or within 24 hours of adding the fortifier.

  • Breast milk is not homogenised so the fat will separate from the milk. Swirl gently to mix.

  • Never add fresh warm breast milk to milk that is already cold or frozen. First chill the milk that is to be added.

Warming breast milk

  • To warm breast milk stand the container in warm water. Do not use boiling water this will curdle the milk and destroy the milk's anti-infective properties.

Thawing frozen breast milk

  • To thaw frozen breast milk place the breast milk in the refrigerator for several hours, or stand it in warm water changing the water several times to maintain its warmth, or stand the sealed container under running cold water.

  • NOTE: Microwaves should never be used to heat breast milk because they destroy the immunological properties and some vitamins and disturb protein formation. Microwaves also heat unevenly, so microwaved milk can scald babies.

Feeding baby expressed breast milk

  • Use either a sterilised infant feeding bottle or a small cup.

  • Gently shake the warmed milk, test the temperature by a few drops on your wrist.

Transporting breast milk

  • Use and insulated container e.g. a styrofoam chest or chillybin with an icepack to transport expressed milk.

  • Breast milk may be stored up to 24 hours in a styrofoam chest with an icepack.

  • If no styrofoam chest or chillybin is available wrap container well in several layers of newspaper for transporting short distances.

Cleaning and sterilising* equipment

  • Wash your hands before handling equipment used of storing, feeding or expressing breast milk.

  • Rinse all equipment to be used under cold water, wash with warm soapy water, and then rinse well again. Use a clean bottle brush to clean inside containers and bottles.

  • Teats may be rubbed inside with salt to remove traces of milk, and then well rinsed.

  • Sterilise plastic containers, feeding or expressing equipment in sterilising solution (e.g. Milton's) for 1 hour or submerged in boiling water for 5 minutes.

  • Sterilising tablets and equipment to make sterilising solution are available from pharmacies and supermarkets. Sterilising solutions can be used for 24 hours before being changed. The manufacturer's instructions must be carefully followed to prepare the correct strength and soak for the recommended time.

  • For Hospital use - equipment is autoclaved between being used by different mothers.

*At home the term 'sterile' refers to the use of an antibacterial solution such as Milton's, or heat treatment such as boiling method. This term applies to the home environment when the equipment is used by the same mother and baby.

In hospital all items that are used between mothers and babies such as breastpump accessories or some feeding equipment are sterilised by autoclaving by CSSD (Central Sterile Supply).


  1. Breastfeeding A Guide for the Medical Profession. R.A., R.M. Lawrence. 1999