Expressing, handling and storing breast milk factsheet


Breastfeeding your baby is considered the optimum feeding practice, but there are certain times and situations when this is not possible. When this occurs, expressing your breast milk can help to preserve your breast milk supply and also ensure that your baby is able to receive breast milk at a later time.

 Things to consider

Expressing Breast Milk

Breast milk can be expressed by hand or by using a breast pump.

Hands must be clean and containers and equipment should be sterile. Your health professional can help to provide support and guidance on the use of expressing equipment and the correct technique to suit your personal needs. 

Expressing should occur 6-8 times a day (about every 3 hours). The duration of expressing will vary between individual mothers, however usually 20-30 minutes is needed to adequately drain both breasts.

If your baby is unable to feed at the breast, expressing at least once during the night is important for ongoing milk supply. Expressing may need to continue until your baby is taking full breastfeeds.


Hand expressing

This method can boost milk production. The following steps should be followed:

  1. Wash hands.
  2. Gently massage the whole breast with the palms of the hands moving in a circular motion from the outside of the breast towards the nipple.
  3. Repeat this several times and then, gently roll the nipple between the thumb and index finger (much like making a fingerprint).
  4. Hold a clean container or capped syringe under the breast to catch the milk.
  5. Place the thumb and fingers diagonally on the edge of the areola (dark tissue surrounding the nipple).
  6. Gently press inwards towards the centre of the breast squeezing the finger and thumb together gently.
  7. Continue in a rhythmical rolling motion until the milk starts dripping. It may take a little time for milk to flow. It should not be painful.
  8. Change the position of the fingers as the milk stops dripping from the area of compression and start again.
  9. Express until the breast is drained. Switch between breasts when the flow slows for up to 20-30 minutes.
  10. Ensure expressed milk is labelled with date and time expressed and stored correctly.

Using a manual or electric breast pump

Manual or hand breast pumps are portable and typically used short-term or infrequently. A good manual breast pump should produce a controllable suction, be easy to use, be easy to clean, and not cause any pain.

Electric breast pumps can allow for double-pumping (expressing both breasts at the same time) and can be used long-term. There are many brands available for purchase or hire. Speak to your health professional about the most suitable option for your pumping needs.

The following steps should be followed when using a manual or electric breast pump:

  1. Wash hands
  2. Ensure equipment is clean prior to use
  3. Gently massage the breast using the palm of the hand
  4. Position the nipple in the centre of the breast shield
  5. Use the pump according to the instructions. Most manual pumps will use a trigger-like action. Electric pumps will often have program settings to create variation in pumping pressure and intensity.
  6. Express until the breast is softer or for about 10-15 minutes until flow stops. Repeat on the other breast. Switch between breasts more frequently as the flow slows.
  7. The process should be pain free if performed correctly. If pain occurs, stop expressing and seek advice from your healthcare professional (GP, Midwife, Child and Family Health Nurse, Lactation Consultant).
  8. Ensure expressed milk is labelled and stored correctly
  9. Clean equipment after use.

Sterilising equipment

Personally owned expressing equipment does not need to be sterilised for a healthy term baby. If you are expressing several times a day, your equipment should be rinsed well in cold water after each use to remove any milk residue and be given a thorough clean at least once every 24 hours. The expressing equipment should be stored in a clean, closed container in between uses.

 The following steps should be followed when cleaning expressing equipment:

  1. Wash hands
  2. Take apart all parts and rinse with cold water to remove any milk residue.
  3. Hot water, a designated cleaning brush and a small amount of dishwashing liquid should be used to remove all traces of grease, milk and dirt.
  4. Each part should be rinsed twice in hot water.
  5. Place bottles upside down on clean paper towel or cloth to air dry. If water droplets are present, dry carefully prior to putting away and ensure no wetness remains.
  6. Store in a clean, covered container until next use.
  7. As an alternative, expressing equipment and bottles can also be cleaned using boiling water. Immerse the items in boiling water for 5 minutes.

If using a commercially available sterilising solution to clean equipment such as Milton®, perform the following steps:

  1. Wash bottles, teats and breastfeeding equipment in warm soapy water, then rinse in cold water.
  2. Prepare the solution using 2 Milton® tablets per 4 litres of water.
  3. Add items, ensuring that they are completely immersed in the solution and no air pockets exist. Close the lid and wait for at least 15 minutes for sterilisation to occur before removing any items.
  4. Items can stay in the solution until needed.
  5. If new items are added all items need to remain in for 15 minutes to ensure that they are sterilized.
  6. Renew the solution every 24 hours.

To clean the equipment using boiling water:

  1. Put the equipment including bottles and teats in a large pot.
  2. Fill the pot until the equipment is covered with water.
  3. Using the stove top, bring the water to boil.
  4. Let everything cool before removing from the pot.

For  alternative methods, including using commercial quick clean microwave sterilising bags or electric steam sterilising units, please follow the specific directions of the manufacturer.

Thawing and warming breast milk

It is normal for expressed breast milk to separate into layers when frozen. Once thawed, it can easily be mixed by gently shaking the container.

Frozen breast milk can be thawed using 2 methods:

  • For quick thawing, place the container of expressed breast milk into a bowl of warm water. As the water cools, add a bit more hot water to the bowl. Continue to gently swirl the container until the milk becomes liquid. Do not use boiling water.
  • If the expressed milk is not required immediately, it can be thawed slowly by leaving it in the fridge for several hours or overnight. It should not be left to thaw at room temperature.

Heating breast milk

Expressed breast milk does not need to be boiled prior to feeding your own baby.

In order to warm chilled or thawed expressed breast milk, place the container in a bowl of hot water or an electric  bottle warmer until the milk reaches body temperature.  Check the temperature is suitable by dropping a small amount onto your wrist. It should feel warm but not hot.

A microwave oven should not be used to heat or thaw milk, as it can destroy some of the nutrients and also heats unevenly which may cause scalding. 

Storing expressed breast milk

Freshly expressed into container

Room temperature (26⁰C or lower)6-8 hours, refrigerate milk if possible
Refrigerator (5⁰c or lower)No more than 72 hours, store in back of refrigerator, where it is coldest
Freezer2 weeks in freezer compartment inside refrigerator (-15⁰C)
3 months in freezer section of refrigerator with separate door (-18⁰C)
6-12 months in deep freeze (-20⁰C)*

*Chest or upright manual defrost deep freezer that is opened infrequently and maintains ideal temperature

Previously frozen – thawed in refrigerator but not warmed

Room temperature (26⁰C or lower)4 hours or less
Refrigerator (5⁰C or lower)24 hours
FreezerDo not refreeze

Thawed outside refrigerator in warm water

Room temperature (26⁰C or lower)For completion of feeding 
Refrigerator (5⁰C or lower)4 hours or until next feeding 
FreezerDo not refreeze

Infant has begun feeding

Room temperature (26⁰C or lower)Only for completion of feeding 
Refrigerator (5⁰C or lower)Discard milk
FreezerDiscard milk
Last updated Friday 9th February 2024


This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2024