How to Store Breast Milk in Bags: The Ultimate Guide

Breast milk is the most natural and nutritious food for a newborn baby. It contains all the essential nutrients that a baby needs for optimal growth and development. However, some mothers are not always available to breastfeed their babies due to work, travel, or other reasons. To ensure that your baby continues to receive this vital nutrition, you will need to express your milk and store it properly. One of the most common ways to store breast milk is by using bags. In this article, we will guide you on how to store breast milk in bags.

Understanding the importance of storing breast milk

Storing breast milk is essential for mothers who cannot always be with their babies. By expressing and storing breast milk, mothers can ensure that their babies receive a continuous supply of nutritious milk even when they are away. Storing breast milk properly helps to maintain its quality and prevent contamination by bacteria, which could make your baby sick.

How to express and collect breast milk

Wash your hands

Before collecting breast milk, it is essential to wash your hands properly with soap and water. This helps to prevent the transfer of bacteria into the milk.

Choose the right container

The most commonly used containers for collecting breast milk are bottles or bags. Ensure that the container is washed and sterilized before each use.

Manual expression

To express breast milk manually, place your thumb and forefinger around the nipple and squeeze gently. You should feel a steady flow of milk from the breast.

Using a breast pump

Using a breast pump is an efficient way to express breast milk. There are two types of breast pumps: electric and manual pumps. Electric pumps are faster and more comfortable, while manual pumps are cheaper and more portable.

How to store breast milk in bags

Choose the right bags

The most commonly used bags for storing breast milk are specially designed milk storage bags. They are made of plastic and are pre-sterilized to prevent bacterial contamination. Ensure that the bags are BPA-free and are of good quality.

Label the bags

Label each bag with the date and time that you expressed the milk. This helps you to know which milk to use first and prevents milk wastage.

Fill the bags

Fill the bags with the amount of milk that your baby needs for each feeding. Avoid filling the bags to the brim as the milk will expand when it freezes.

Remove air from the bags

Squeeze out all the air from the bag before sealing it. This helps to prevent freezer burn and prolongs the storage life of the milk.

Store the bags

Place the bags in the freezer immediately after expressing the milk. Store them flat in the freezer to save space and ensure that they freeze quickly. Avoid storing the bags in the door of the freezer as the temperature may fluctuate and affect the quality of the milk.

How long can breast milk be stored in bags?

The length of time that breast milk can be stored in bags depends on the storage conditions.

  • Room temperature (up to 77°F or 25°C): 4 hours
  • Refrigerator (at 32-39°F or 0-4°C): Up to 4 days
  • Freezer (at 0°F or -18°C): Up to 6 months or 12 months

The storage times can vary depending on the quality of the milk, the storage conditions, and the type of freezer or refrigerator you are using. It is always best to use the oldest milk first and follow the standard storage guidelines to ensure that your baby receives fresh and nutritious milk.

How to thaw and warm breast milk

Thawing breast milk

You can thaw breast milk by placing the bags in the refrigerator overnight or by thawing them under warm running water. Do not thaw breast milk in the microwave as it can destroy the nutrients and heat the milk unevenly, which may cause burns to your baby.

Warming breast milk

You can warm breast milk by placing the bag in a bowl of warm water or by using a bottle warmer. Do not heat breast milk in a microwave or over direct heat as it can cause hot spots and reduce the nutritional value of the milk.


Storing breast milk in bags is a convenient and efficient way to ensure that your baby receives the essential nutrients from your milk even when you are away. To store breast milk properly in bags, follow the guidelines provided above, including proper expression and collection, bag selection, labeling, removing air, and storing in the freezer. Always follow the standard storage guidelines to ensure that your baby receives fresh and nutritious milk whenever needed.


  • Can I reuse milk storage bags?
  • No, milk storage bags are designed for single-use only. Reusing them can lead to bacterial contamination and affect the quality of the milk.

  • What should I do if I spill some breast milk?
  • If you spill some breast milk, clean it up immediately with soap and water. Do not leave it to dry as it can attract bacteria and cause contamination.

  • What if I have leftover breast milk after a feeding?
  • You can store the leftover breast milk in the refrigerator or freezer immediately after the feeding session. Use it within the recommended storage time to maintain its quality and nutritional value.

  • How do I know if the breast milk is spoiled?
  • Spoiled breast milk may have an off smell or appearance, and it may contain curdled or lumpy milk. Do not use it, as it may cause an upset stomach or bacterial infection to your baby.


  1. Academy of Breastfeeding Medicine. Clinical Protocol #8: Human Milk Storage Information for Home Use for Full-Term Infants, Revised 2017. Breastfeed Med 2017;12(7):390-395.
  2. Centers for Disease Control and Prevention. Proper Storage and Preparation of Breast Milk. Updated June 9, 2020. Accessed September 12, 2021.
  3. La Leche League International. Expressing Milk for Your Baby. Updated June 22, 2021. Accessed September 12, 2021.

Leave a Reply

Your email address will not be published. Required fields are marked *