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Expressing (Pumping) and Storing Breast Milk

How to express by hand or pump and general storage times.

Before you use this guide: This is general educational information, not an individual medical assessment. We do not identify a clinician reviewer on this page, so please confirm personal health decisions with your doctor, midwife or paediatrician.

Expressing milk lets someone else feed your baby, helps you build or protect your supply, and eases fullness. If you are breastfeeding without any problems, many mothers wait until breastfeeding is well established, often around the first month, unless their care team advises otherwise. If your baby is premature, unwell or cannot feed at the breast, you may begin expressing in the first hours.

Ways to express

• Hand expressing: free, always available and especially useful for small amounts of colostrum in the first days. A midwife can show you how.
• Manual pump: small, quiet and cheap, and good for occasional use.
• Electric pump: faster, and a double pump lets you do both sides at once. Hospital-grade pumps can be rented.

Expressing tips

• Wash your hands and use clean equipment.
• Find a quiet, comfortable place and think of your baby, or look at a photo or video.
• Apply warmth to the breast and massage gently before you start. Many mothers find expressing easier right after a feed.
• Start with a gentle setting to trigger your let-down, then increase the suction to a comfortable level.
• Pumping should not hurt. If it does, check that the flange (breast shield) size is right, so your nipple moves freely without rubbing, and reduce the suction.
• Expect small amounts at first. Output varies widely, and it is not a measure of your supply or how much your baby gets from a feed.

How often to express

To keep up your supply when you are away from your baby, try to express at about the times your baby would feed, which is roughly every three hours, or about eight times in 24 hours if you are exclusively pumping. If you are going back to work, start building a small store a few weeks before. Our guide to returning to work has more planning tips.

Storage guidelines

Guidelines vary by country, so follow your local health advice. Commonly cited times for freshly expressed milk are:

• Room temperature (up to about 25 °C / 77 °F): up to about 4 hours
• Fridge (at about 4 °C / 39 °F or colder): up to about 4 days. Some health services allow a little longer if the fridge is very cold and monitored. If you are unsure, use the shorter time.
• Freezer: around 6 months for best quality
• Insulated cool bag with ice packs: up to about 24 hours

Storing and labelling

• Use clean, sealed containers or breast milk storage bags that are made for the purpose.
• Label each with the date and, if you are using childcare, your baby's name.
• Store in small amounts, such as 60 to 120 ml (2 to 4 oz), to reduce waste, and leave space at the top because milk expands when frozen.
• Store at the back of the fridge, not in the door, and freeze bags flat to save space and thaw quickly.
• Cool freshly expressed milk in the fridge before adding it to milk that is already cold or frozen. Do not add warm milk to frozen milk.
• Use the oldest milk first.

Thawing and warming

• Thaw frozen milk in the fridge overnight, or hold the container under warm running water or in a jug of warm water.
• Do not microwave it, because it heats unevenly and can scald your baby's mouth. Do not boil it.
• Gently swirl the milk. It is normal for it to separate, with the fat rising to the top.
• Test the temperature on the inside of your wrist. Milk does not need to be warm, and some babies will take it cool.
• Use thawed milk within about 24 hours and do not refreeze it. Throw away milk left in a bottle after a feed.

Milk from a freezer can sometimes smell soapy or sour because of natural enzymes, and it is usually still safe if it was stored properly. If it smells very bad, throw it away.

Keeping equipment clean

• Wash your hands before expressing and touching pump parts.
• After each use, take apart the pump parts that touch milk, rinse them, then wash in hot, soapy water, rinse and air dry on a clean surface. Many are dishwasher safe, so check the instructions.
• Sterilise parts at least once a day for babies under three months, or if your baby was premature or is unwell.
• Do not wash the tubing, which does not touch milk, unless it gets milk inside it.

Feeding expressed milk

• Some babies need a few tries to take a bottle. Wait until breastfeeding is established, usually around three to four weeks, then try offering a bottle now and then. Ask someone else to give it, because babies often refuse it from the mother.
• Use a slow-flow teat, hold your baby semi-upright and let your baby control the pace (paced bottle feeding).
• Cups and spoons are also an option, particularly for small amounts.

If something is not working

• Low output: relax, use warmth, look at a photo of your baby, check the flange size, and try expressing after a feed. Ask a lactation consultant for help if you are worried.
• Pain or damaged nipples: stop and check the flange size and settings. See our guide to common breastfeeding problems.
• A hard lump or a red, painful breast, particularly if you miss expressing sessions: see your doctor, because this could be mastitis.

Donor milk

If you cannot supply enough, some countries have milk banks that provide screened donor milk, usually for premature or sick babies. Informal milk sharing carries infection risks, so talk to your doctor before considering it.

Where to check current advice

Storage times differ slightly between organisations, so check the latest advice from your own health service, such as the NHS in the UK, the HSE in Ireland, the CDC in the US, the Canadian Paediatric Society in Canada and the Australian Breastfeeding Association in Australia.

This content is for general information only and is not medical advice. Every pregnancy and every baby is different. Always talk to your doctor, midwife or paediatrician about your own situation, and seek urgent care if you are worried.