How to Safely Freeze and Store Breast Milk in Liquid Bags

freezer storage device

Breast milk is the perfect food for newborns, providing all the nutrients they need to grow and develop. As a breastfeeding mother, you may need to pump and store your milk for various reasons such as going back to work, going out for the night, or having a medical issue that temporarily prevents you from breastfeeding. Whatever the reason may be, it is important to properly store and freeze breast milk to preserve its nutritional value and prevent contamination.


freezer storage device

In this article, we will discuss how to safely freeze and  store breast milk in liquid bags. We will cover the best practices for handling breast milk, the types of bags that are safe for storage, how to label and store breast milk, and how to thaw and warm it up when you are ready to use it.

Types of Bags for Breast Milk Storage

The first step in freezing and storing breast milk is choosing the right type of bag. There are several options available in the market, including plastic bags, glass bottles, and silicone bags. However, not all of these options are safe for storing breast milk.

Plastic bags are the most commonly used option for storing breast milk, but not all plastic bags are created equal. It is important to choose bags that are specifically designed for breast milk storage, as they are made of food-grade plastic and are BPA-free. These bags have a special design that allows them to be stored flat in the freezer, making them a space-saving option.

Glass bottles are also an option, but they are not as convenient as plastic bags as they take up more space and can break easily. Silicone bags are a newer option that is becoming more popular. They are reusable and can be washed and sterilized, making them an eco-friendly option.

Labeling and Storing Breast Milk 

Once you have chosen the right type of bag, it is important to label it with the date and time that the milk was expressed. This will help you keep track of the freshness of the milk and ensure that you use the oldest milk first. You can use a permanent marker to write the date and time on the bag.

When storing the breast milk, make sure to leave some room at the top of the bag for the milk to expand when it freezes. Do not overfill the bag as this can cause it to burst or leak. Lay the bags flat in the freezer to save space and allow the milk to freeze faster. Once the milk is frozen, you can stack the bags on top of each other.

It is important to store breast milk in the back of the freezer, away from the door, as this is the coldest part of the freezer. Avoid storing breast milk in the door as it is subject to temperature fluctuations every time the door is opened, which can cause the milk to thaw and refreeze.

Thawing and Warming Up Breast Milk

When you are ready to use the breast milk, it is important to thaw it safely. The best way to thaw breast milk is to transfer the bag from the freezer to the refrigerator and let it thaw overnight. This allows the milk to thaw slowly and safely.

If you need to thaw breast milk quickly, you can place the bag in a bowl of warm water or hold it under running warm water. Do not use hot water or a microwave to thaw breast milk as this can destroy the nutrients and cause hot spots that can burn your baby’s mouth.

Once the breast milk is thawed, you can warm it up by placing the bag in a bowl of warm water or using a bottle warmer. Do not warm up breast milk on the stove or in the microwave as this can cause hot spots and destroy the nutrients.

Best Practices for Handling Breast Milk 

In addition to choosing the right type of bag and properly storing breast milk, there are some best practices for handling breast milk that can help ensure its safety and quality. These include:

  1. Wash your hands thoroughly before expressing or handling breast milk to prevent contamination.
  2. Use clean and sterile equipment to express and store breast milk. This includes breast pumps, storage bags, and bottles.
  3. Do not mix freshly expressed breast milk with previously frozen breast milk. If you need to combine milk from different pumping sessions, make sure they are both chilled in the refrigerator before mixing.
  4. Avoid shaking breast milk vigorously as this can break down the proteins and nutrients. Instead, gently swirl the bag to mix the fat that may have separated.
  5. Do not refreeze thawed breast milk. Once it is thawed, it should be used within 24 hours.


In conclusion, properly freezing and storing breast milk in liquid bags is crucial for preserving its nutritional value and preventing contamination. When choosing a bag, it is important to select a bag specifically designed for breast milk storage, such as a BPA-free, food-grade plastic bag. It is also important to label the bag with the date and time of expression, leave room for expansion during freezing, and store it in the back of the freezer.

Thawing and warming up breast milk should be done safely and slowly, either by transferring the bag to the refrigerator overnight or by using warm water. Remember to never thaw breast milk in hot water or a microwave, as this can destroy its nutrients and create hot spots.

By following these best practices and handling breast milk with care, you can ensure that your baby receives the best possible nutrition and reduce the risk of contamination. Proper storage and handling of breast milk is an essential part of breastfeeding and can provide peace of mind for both mother and baby.