Mum Baby Shoulder


Have these stages personalized and emailed to you: Sign up now

Expressed milk: Your questions answered

Does it have a best before date? And how exactly do you get it out? We have the answers to some of your most common questions when it comes to expressing breast milk.

What does ‘expressing milk’ mean?

Expressing milk means the same thing as pumping milk. It’s a way of taking milk from your breasts without your baby needing to breastfeed directly (NHS Choices, 2014). You can do this using your hands, a manual pump or an electric breast pump.

Using expressed milk can be handy for women for many different reasons. Some people may do it because they have babies who can’t feed. Others because they may want to allow a partner or other family members to get involved in feeding.

Do I have to express milk if I’m breastfeeding?

Not at all. Only do it if it’s something that works for you and your baby. If you do decide to express, you should wait until you and your baby are in the habit of breastfeeding. Around three to six weeks in is often said to be an adaptable, flexible time to see whether your baby takes a bottle (University Hospital Southampton NHS Trust, 2014).

How long should I express for?

A session can take anywhere between 15 and 45 minutes as you pump both of your breasts. Put on your favourite TV show, get comfortable and express your milk for as long as it is flowing well rather than letting time guide you.

Do I really need to sterilise everything I use to express milk?

Yes. It’s important that you clean and sterilise any containers or parts that your milk touches, like pumps, bottles, cups and spoons (NHS Choices, 2016). You must do this each time you use them until your child is at least 12 months old (NHS Choices, 2016).

Does expressed breast milk need warming up?

Babies don’t need their milk warm but some prefer it at body temperature. The safest way is to stand it in a jug of warm water.

Warm the milk just enough to take the chill off and shake out a few drops onto your wrist to test. Never heat milk in a microwave as it can lead to uneven heating and burn a baby’s mouth (American Academy of Pediatrics, 2011; NICE, 2014).

How much milk will I need for one feed?

Babies differ so much and while young babies can only take around a few millilitres at a time, older babies will of course take more. Your baby’s appetite may be bigger on some days, just like yours.

If you still want a rule of thumb, leave at least 100 ml for every feed, plus some extra. Try that until you get to know your baby’s habits.

How do I store expressed milk in the fridge?

Store milk in sterilised containers or in plastic bags made specifically for storing milk. Write on them the date and use up the oldest first (NICE, 2014).

You can store freshly-expressed milk for up to five days in the main part of a fridge, at 4°C or lower (NICE, 2014). If you’re not sure of the temperature or if it’s higher than that, use it within three days.

Go for the fridge as your first option as freezing breast milk destroys some of its biologically active components (Piela et al, 2017). If you need it on the go, you can store your refrigerated breast milk for four hours in a cool bag or box with ice packs in it. If you stored it at room temperature, you need to use it within two hours (UNICEF, 2015).

How do I store expressed milk in the freezer?

In the freezer compartment of a fridge, you can store expressed breast milk for two weeks. If you store your breastmilk in a stand-alone freezer, it’ll last up to six months at as long as it’s at -18°C or lower (NICE, 2014).

How do I thaw frozen breast milk?

You can thaw frozen milk by defrosting it in the fridge (NICE, 2014). Don’t be tempted to speed up the thawing or warming process, and never use a microwave to warm or defrost your milk (NICE, 2014).

Once milk is thawed it can separate so give it a shake. Use it straight away and throw away any that’s left. If it smells sour throw it out.

Is it normal for expressing breast milk to be painful?

Expressing milk shouldn’t be painful. If you’re finding it difficult, speak to your midwife (NHS Choices, 2017).

Is there anything else I need to know about expressing breast milk?

Yes, the more relaxed you are the easier it will be. The hormone oxytocin is released when you’re feeling happy and relaxed, and that’s what causes your milk to be let down. Having your baby or a picture of your baby nearby or smelling their clothes can help.

This page was last reviewed in October 2017

Further information

Our helpline offers practical and emotional support in many areas of pregnancy, birth and early parenthood: 0300 330 0700.

You might find attending one of our Early Days groups helpful as they give you the opportunity to explore different approaches to important parenting issues with a qualified group leader and other new parents in your area.

Make friends with other parents-to-be and new parents in your local area for support and friendship by seeing what NCT activities are happening nearby.

NCT supports all parents, however they feed their baby. If you have questions, concerns or need support, you can speak to a breastfeeding counsellor by calling our helpline on 0300 330 0700, whether you are exclusively breastfeeding or using formula milk. Breastfeeding counsellors have had extensive training, will listen without judging or criticising and will offer relevant information and suggestions. You can also find more useful articles here.

National Breastfeeding Line (government funded): 0300 100 021. has a comprehensive library of face-to-face interviews where parents share their experiences about breastfeeding, birth, parenting and many other issues.

NHS Choices has information on bottle feeding and breastfeeding in public.

Best Beginnings has video clips from the 'Bump to Breastfeeding' DVD.