Dear mum,
It's wonderful that you want to give your baby breast milk! But sometimes it's not possible to breastfeed right away—for example, if you're going back to work, exercising, or simply want to catch up on sleep while your partner takes over. That's where expressed breast milk comes in! It's a great alternative and still offers your baby many health benefits.
To ensure that your precious breast milk stays safe and sound, there are a few simple rules for storage.
1. When is the best time to pump for storage?
Many midwives recommend not pumping milk for freezing during the first two weeks after birth . There are two good reasons for this:
-
You and your baby can first find your own breastfeeding rhythm.
-
During this time, your body adjusts to your baby's needs. Breast milk is constantly changing to provide the exact nutrients your baby needs (from colostrum to transitional milk to mature milk). Older, frozen milk may no longer perfectly meet your baby's current nutritional needs.
2. Choose the right containers
The right containers are important for storing your expressed milk:
-
Special breast milk bags: These are particularly hygienic , often pre-sterilized, and feature a practical scale and a date code. Some can even be connected directly to the breast pump. They also save space in the freezer. Medela, for example, offers special breast milk bottles and bags that make collecting and storing milk safe and easy. Medela's Easy Pour breast milk bags are ideal for freezing and easy to label.
-
BPA-free breast milk bottles: Make sure they are made of BPA-free materials.
-
Jars with screw caps: An environmentally friendly choice! Make sure the jars are cold-resistant so they won't burst in the freezer. They're easy to clean (rinse with dish soap and hot water, let them air dry).
-
Avoid: Regular freezer bags or ice cube trays are not ideal because they contain plasticizers or do not adequately protect the milk from germs.
-
Standards & safety : Look for products that comply with DIN EN 14350 (2023) for drinking equipment; this standard tests the materials, construction, and labeling of baby bottles and pouches for safety.
-
EU rule on the BPA ban : Bisphenol A has been banned for baby bottles across the EU since 2011; permitted materials include polypropylene (PP), polyethylene (PE), and PET, identified by the recycling codes 01, 02, or 05.
Tip: Transparent containers or those that you can easily label are very practical
3. Prepare breast milk for freezing
-
Hands and environment: Always start with clean hands and a clean work surface.
-
Pre-cooling: Expressed milk is at body temperature. Therefore, always let it cool in the refrigerator before placing it in the freezer.
-
Do not mix: Never add body-temperature, freshly expressed milk to already chilled or frozen milk . If you want to mix different portions, chill them separately first and then mix them.
-
Fill portions: Only fill the containers three-quarters full, as the milk expands when frozen. Small portions (e.g., 60-120 ml) are ideal to avoid waste. You can also mix several thawed portions later if needed.
-
Label: Very important: Write the pumping date and the amount on each container . This way, you can keep track of your "milk bank" and use the oldest milk first.
-
Storage : Store lids and seals separately in the refrigerator until the milk is added to avoid condensation and the formation of germs.
4. Store breast milk properly
The shelf life of breast milk depends on where you store it. Here are the general guidelines for healthy, full-term babies :
-
At room temperature (16-25°C): Ideally, a maximum of four hours . Under very hygienic conditions, up to six hours. In summer, temperatures above 22°C only a few hours.
-
In the refrigerator (4°C or colder): Ideally, a maximum of three days . Under very hygienic conditions, up to five days. Some sources also mention up to four days at 0-4°C. Immediately after pumping, place the milk in the coldest part of the refrigerator, ideally at the very back above the vegetable drawer. Do not store it in the refrigerator door , as the temperature fluctuates there.
-
In the freezer (-18°C or colder): Ideally, a maximum of six months . Under very hygienic conditions, up to nine months. Some experts consider the quality acceptable even after six additional months. Place the milk at the very back of the freezer, where the temperature is most consistent. Make sure containers are not touching the walls in self-defrosting freezers.
-
Important note regarding the freezer compartment in your refrigerator: If you only have one freezer compartment in your refrigerator, you should use the milk within one to two weeks , as the temperature there can fluctuate more.
-
Antibacterial effect: The important vitamins, proteins and fats are retained when frozen, but the antibacterial effect is lost after about three weeks .
Information : For premature, very small, or immunocompromised babies, professional associations recommend even stricter times: a maximum of 24 hours in the refrigerator and 3 months in the freezer ≤ -18°C; all pump parts should be sterilized daily.
5. Thaw and warm frozen breast milk properly
Patience is important when thawing to ensure that the valuable nutrients are preserved.
-
Thawing:
-
In the refrigerator: This is the best method and takes about 12 hours.
-
Under running water: Hold the bottle or bag under cold or lukewarm running water (max. 37 °C).
-
In a water bath: Fill a bowl with warm (not hot) water and place the container with the milk inside. Make sure no water gets into the milk.
-
With a bottle warmer: You can also use a special bottle warmer, ideally with a defrost function.
-
NEVER thaw or heat in a microwave or boiling water ! This destroys nutrients, can create hot spots, and burn your baby.
-
Do not refreeze thawed milk .
-
Shelf life after thawing:
-
At room temperature: Maximum two hours after complete thawing.
-
In the refrigerator: Up to 24 hours . An unopened container will keep for 24 hours, an opened container for 12 hours.
-
Heat:
-
Is warming necessary? Not necessarily! Many babies enjoy drinking milk at room temperature.
-
Desired temperature: If your baby prefers warm milk, it should be around 35-37 °C (body temperature) .
-
How to warm it? Place the milk bottle or bag in a cup, jug, or bowl of lukewarm water (max. 40°C) for a few minutes. Or use a bottle warmer.
-
Avoid shaking: Gently swirl the bottle to re-mix the separated fat with the milk. Vigorous shaking can damage the valuable ingredients.
-
Check temperature: Place a drop of milk on the inside of your wrist to make sure it is warm but not too hot.
-
Dispose of leftovers: Only give your baby as much milk as they need for one feeding. Any leftover, warmed, or partially consumed milk should be thrown away after one to two hours at the latest .
6. If breast milk smells strange
Sometimes cooled or thawed breast milk smells slightly soapy or rancid . This is normal and is due to an enzyme called lipase, which breaks down fats. If you've followed all storage instructions, the milk is safe for your baby . However, your baby may reject it because of the altered taste.
6.1 If the milk smells soapy – Lipase management
|
Step |
gentle solution |
|
1. Cool quickly |
Place freshly expressed milk in the refrigerator immediately (≤ 30 min.). |
|
2. Scalding |
Heat milk in a saucepan to approximately 82°C (small bubbles at the edge), immediately place it in an ice/cold water bath, and then refrigerate or freeze as usual. This inactivates the excess lipase, leaving the flavor neutral while minimizing nutrient loss. |
|
3. Mix instead of throwing away |
Combine the rejected portion proportionally (e.g. ⅓) with fresh milk – many babies accept the milder taste. |
|
4. Taste training |
Some babies get used to the soapy taste within a few days if it is increased gradually. |
7. Store breast milk on the go
When transporting breast milk, for example, from work to home, use a cooler bag with ice packs . Small cooler boxes or thermos flasks are also an option. Always make sure to protect the milk from extreme temperature fluctuations. At room temperature, the milk should be consumed within four hours at the latest.
8. How do I know if breast milk is no longer good?
Trust your senses! If the milk shows any of these signs, you should throw it away:
-
A sour or rancid smell .
-
The color has changed , or there are lumps or discolorations.
-
An unusual or bitter taste .
-
Your baby suddenly refuses milk or shows signs of discomfort. (Make sure there aren't other reasons for the refusal.)
-
Texture check: Uniform consistency – heavy lumps or gel formation indicate spoilage.
-
Color signals: Gray, pinkish-red, or greenish streaks may indicate bacterial growth.
-
Separation of layers: A thin fat layer is normal; however, if a grainy residue remains after gentle tossing, discard the portion to be on the safe side.
-
Mold/spots on bottle wall: discard immediately.
Baby's reaction: Increased spitting up, diarrhea, or refusal may be late signs of spoiled milk.
When in doubt : Better safe than sorry. It's always better to discard the milk if you're unsure.
9. Hygiene Guide: Cleaning & Sterilizing Your Breast Pump (Step-by-Step)
-
Wash hands for 30 seconds and prepare a clean work surface.
-
Completely disassemble the pump – breast cap, valves, membranes, etc.
-
Pre-rinse with cold water to remove milk residue.
-
Soak in warm soapy water (≥ 60 °C) in a separate bowl; clean all parts with a bottle brush.
-
Rinse thoroughly and air dry on a fresh cloth – do not rub!
-
Dishwasher safe (high temperature program) ; place small items in the cutlery basket/laundry net.
-
Sterilize:
-
Boil for 5 minutes in boiling water
-
Steam vaporizer or dishwasher with sterilization program
-
Sterilize daily if baby is < 2 months old, premature or ill.
-
Avoid common mistakes: sterilizing for too short a time, storing in humid conditions, and microwaving without approved sterilization bags.
The most important things in brief:
-
Hygiene is paramount.
-
Freshly expressed milk is best, chilled milk is better than frozen milk.
-
Always write down the pumping date.
-
Do not store leftovers.
-
Never use a microwave or boiling water for heating.
If you have any further questions or are unsure, always contact your midwife, lactation consultant or doctor.
