Guide to Storing Breast Milk

Breast milk is proven to be the best food source for a newborn baby till up to six months of his life. Even after six months, pediatricians recommend continuing to feed the baby for up to two and a half years. Given a baby feeds anywhere from 10-12 times a day, it can be hard to breastfeed all the time, especially for working moms. In recent years, science has come up with an efficient solution for pumping and storing breast milk, so it can be given to the baby from a bottle. This is beneficial when the mom is not home or if a baby needs to be fed in social situations.

How to Pump Breast Milk?

There are two types of breast pumps available in the market: manual pumps and electric pumps. While manual pumps are cheaper, the work required to pump by hand can be strenuous, especially if you pump frequently. Electric pumps establish an automatic suction, and this method of pumping is easier and less tiring, which makes it the preferable way of pumping to most mothers. 

Before starting to pump, wash your hands with soap and water. An alcohol-based sanitizer would work well too. Check that your pump and all the tubing are clean. If there is any visible mold or colored residue in the tubing, throw it out. A slight discoloration of the tubing is fine but you should not have any remains from any previous pumping. Place the conical front (flanges) on the nipple and switch on the pump at high speed and low suction. Once the milk starts expressing itself, switch the pump speed to medium, and alter the suction level according to your comfort. 

Continue pumping for 20 minutes, or until the milk stops. Clean and sanitize all your equipment after each use to avoid the risk of contamination. You can then store the pumped milk in separate bottles or bags for future use. Repeat 10-12 times a day.

A Manual breast pump

How to Properly Store Breast Milk?

After pumping, you can store all milk pumped in 4 hours, in one single bottle. However, it is important to cool the milk beforehand. Do not add room temperature milk to previously cold milk. For safe storage, use either a glass bottle or plastic that is BPA-free. BPA is a chemical that is usually used in the production of plastics and raisins. There have been active measures taken to reduce the use of plastic that has BPA, as BPA is proved to have long-term neurological, immunity, and reproductive problems.

Make sure the container seals tightly and is safe for the freezer. Some glass bottles may crack at very low temperatures. Medical grade breast milk bags are the best choice, as they have printed scales that let you know the amount of milk.  They also don’t take up as much space in the refrigerator as bottles do. Avoid plastic containers with labels reading BPA, soft plastic bags, and Ziploc bags. The milk can then be left at room temperature, put in the fridge, or frozen till it is needed. However, make sure that you refrigerate the milk as soon as it is expressed.

Young mothers can store breast milk for feeding the baby at a later time

If you are storing breast milk in the freezer, make sure to leave some space at the top because milk expands when it freezes. You also need to ensure you don’t store a lot of milk together. Keep each portion equal to how much a baby drinks at one time. Once thawed, human milk cannot be frozen again. 

Label all bottles/bags clearly with the date on which they were pumped, and the amount of milk so it is easier to keep order. Always be sure to place milk in the back of the fridge or freezer, so it maintains a constant low temperature. Milk that is placed in the door is subject to temperature fluctuations every time the door is opened. 

If you need to take frozen breast milk with you anywhere, pack a cooler with ice. Rest your milk bags or bottles inside, and take care to not overcrowd the cooler. Refresh the ice on the way, so the constant cool temperature in the cooler keeps the milk frozen. In case the milk melts on the way, use it immediately on arrival, or it will have to be discarded.

How Long Is Stored Breast Milk Safe to Use?

Breast milk can be left sitting on a countertop at room temperature for up to 4-5 hours. If you’re putting milk in the fridge, it should be okay to give it to the baby for up to 4 days. If you believe you won’t be needing the milk within that period, it is best to freeze it. Frozen breast milk is safe to use for up to 6 months.

It is essential to ensure that the milk remains completely frozen during the storage period. If the milk is thawed, it cannot be refrozen or it will go bad. In instances that you thaw the milk and don’t use it immediately, it can be left at room temperature for up to 4 hours, given that it has not been warmed. 

Important tips regarding feeding a baby with a bottle here – Is There a Wrong Way to Feed a Baby with a Bottle?


How to Use Stored Breast Milk?

If you’ve left the milk at room temperature or in the fridge, it can be given to the baby right away. There is no need to warm breast milk as it is perfectly safe to use cold. However, if your baby is used to warm milk, use an electric bottle warmer, or bring a pot of water to a boil. Keep your bottle inside a plastic bag, and hold the bag in the boiling water for a few minutes. Once you take it out, give the bottle a good shake to mix any fat that might have separated. 

Do not heat the milk in the microwave, as it can cause hot spots and can scald the baby’s mouth. Similarly, don’t heat the milk directly in a pan.  In the case of frozen breast milk, you can thaw the bottle overnight, under running water, or in a bowl of warm water. Do not heat a bottle directly out of the freezer. The milk needs time to come to room temperature before being heated, or it may expire.  Remember, use the oldest bottle you have stored first, as the quality of milk decreases over time. If the baby hasn’t finished his bottle, you can use the leftover thawed milk for up to 2 hours. If it is not used, discard it.

Store breast milk in a refrigerator for use at a later time

How to Identify Spoiled Milk?

With milk of any kind, the smell is considered the best indicator that the milk is safe. Nevertheless, even the smell test can fail to evaluate the safety of breast milk. A strange smell in the milk doesn’t necessarily mean the milk has expired as the smell of human milk depends on diet and medication. In the case of stored milk, the storage container and freezing process can also contribute to the smell. 

Milk that has separated into water and fat is normally considered unsafe for use. However, doctors say it is perfectly natural for the fat in the milk to separate. You should swirl the milk around until it comes back together. If the clumps don’t leave and the milk looks curdled, it is best to drain it. A high lipase concentration in the mother’s milk can also give thawed milk a soapy or metallic smell. It is safe to feed it to the baby unless it has been frozen for more than 12 months or refrozen before.

Suggested Reading – Bottle Feeding Tips for Dads



Pumping milk is a very efficient method of maintaining your baby on a steady breast milk diet, while also managing a life. It is also very useful to store breast milk in advance in case you stop producing. This will help you give your baby the antibodies and nutrients it needs to grow healthy, even after you stop lactating. 

As long as all proper precautions are taken, stored breast milk is perfectly healthy for the baby. However, substandard storage containers, dirty equipment, and incorrect storage risk contamination and milk spoiling. In the end, if there is any doubt that the milk has gone bad, it is better to be cautious and discard it.