Expressing your breast milk

This information explains how to express breast milk for your baby. You can express using your hand or a pump.

We have given you this information because we have advised you to express your breast milk for your baby.

Breast milk gives your baby comfort and nutrition. The milk is easy for babies who are premature or sick to digest. It also helps to protect your baby from infection.

Expressing your breast milk might be needed or helpful when:

  • your baby has been admitted to the neonatal unit
  • your baby is not ready to feed yet
  • you or your baby have a health condition that means you need extra care

When to start expressing

If your baby has been admitted to the neonatal unit (NNU), paediatric intensive care unit (PICU) or children’s ward after birth, you should start expressing by the time your baby is 2 hours old, or as soon as possible after this time.

There are 2 main hormones that are important in breast milk production.

  • Prolactin helps to make your milk.
  • Oxytocin releases milk from your breast.

Both hormones are stimulated by removal of milk, touching your baby and being close to them, breast massage and nipple stimulation.

The more you express, the more breast milk you make.

Hand expressing

For the first few days, we ask you to hand express into a syringe. This is because the milk you make for the first few days (colostrum) is small in quantity and quite thick.

You can use pump expressing when your milk flow increases.

Hand expressing can help to relieve:

  • blocked ducts, which happen when there is a small lump or sore spot in the breast because milk does not flow easily
  • engorgement, which is when your breasts become too full with milk and might feel hard, painful or swollen
  • mastitis, which is an inflammation (swelling) in the breast. An area of your breast might be sore, hot or red. You might also have flu-like symptoms, such as a headache, high temperature (fever) or shivers

You can also use hand expressing for encouraging babies to feed at the breast.

Read more about hand expressing.

How often to express

Babies feed often, so you should try to express about 8 to 12 times in a 24-hour period. This will mimic your baby’s feeding pattern.

You do not need to set fixed times to express. Instead, try and fit it in with your daily routine. This might mean that you express more often in some parts of the day and have longer gaps at other times.

Try to have gaps of no longer than 4 hours during the day, and gaps of 6 hours at night.

It is important to express at least once during the night, between 2am and 4am. This is when your body releases the hormone prolactin, which makes your milk.

Babies usually wake up and feed during the day and night. This routine helps you to breastfeed your baby in a way that responds to their needs.

Storing your breast milk

When you have collected your breast milk, use a sticky label and attach it to the syringe. Write this information onto the syringe:

  • your baby’s name
  • your baby’s date of birth
  • the date when milk was expressed
  • the time when milk was expressed

If you're in hospital, give the milk to the nurse or midwife caring for you or your baby. They store it in the milk fridge or freezer until it's time to use the milk.

If you're expressing at home, keep the milk in the back of the fridge. You can bring the milk to the hospital in a cool bag that has a freezer block in it.

Breast milk can be stored:

  • at room temperature for up to 6 hours
  • in a fridge at a temperature of 5 to 10C for 3 days
  • in a fridge at a temperature of 0 to 4C for 8 days
  • in a freezer at a temperature of -18C for 6 months

Expressing using a breast pump

Around 3 to 5 days after giving birth, the amount of breast milk that you make starts to increase. You might find that it is easier to collect milk in larger amounts by pump.

In the hospital, there are breast pumps for you to use. You can either use a pump and express next to your baby’s bedside, or use the expressing room.

The expressing room has several pumps. Although you might be expressing in this room at the same time as others, it can be a more private and quiet space.

Read more about expressing using a breast pump.

Supporting your milk production

Expressing breast milk in hospital can be stressful, especially if your baby is unwell.

The oxytocin hormone, which releases milk from your breast, does not flow easily if your stress hormones are high.

It is useful to find ways to relax before and when expressing. For example, listen to music that you like and helps you to feel calm. If you are not next to your baby, look at a picture or film of them. Otherwise, you can have a bonding square or one of your baby’s blankets nearby.

Double pumping (expressing from both breasts at the same time using a breast pump) reduces the amount of time that it takes to express.

Try to have regular skin-to-skin contact with your baby. This has been shown to increase milk supply and the likelihood of breastfeeding.

Bliss, the charity for babies born premature or sick, produce a booklet called Skin-to-skin with your premature baby

The best way to support milk production is with your baby at the breast. When your baby is able and showing signs they are ready to feed, you can offer the breast.

Expressing in the neonatal unit (NNU)

In the NNU, it might be helpful to keep a record of the times you express and record the amount of milk you collect. This helps you to see how much milk you make over a whole day. You can also tell if the amount of milk gradually increases each day.

By the time your baby is 14 days old, the amount of milk you produce each day is about 750mls or more.

In the NNU, staff do an expressing assessment 4 times in the first 2 weeks. This helps to find any problems that you have early. It also allows staff to make suggestions that might help increase your milk supply.

Information for partners and family members

Support from the people around you can make a big difference to your experience of expressing.

It's helpful for the people supporting you to understand what is involved with expressing, and how milk production works. Ask them to read the information on this page so they can support you during this time. Talk to each other about what help feels right for you.

These are some examples of how people close to you can help.

  • Expressing takes time and energy. They can help by giving you lots of encouragement.
  • They can help with practical side things. While you are hand expressing, they can use the syringe to collect the milk, store it or take it to the staff.
  • They can help to get the expressing equipment ready and clean it after use.
  • They can help you to get some rest and make sure that you find time to eat and drink.

Useful sources of information

The Breastfeeding Network has information on breastfeeding. 

La Leche League has information and support to help with breastfeeding.

The NHS website has information on breastfeeding. 

Resource number: 4863
Last reviewed: December 2019
Next review: December 2022

Contact us

If you have any questions or concerns about expressing breast milk, contact the team caring for your baby.

Neonatal unit, phone: 020 7188 4045

Breastfeeding team (maternity), phone: 020 7188 7564

Postnatal ward, phone: 020 7188 5149

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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