Layering Frozen Breast Milk

Can You Add More Breast Milk To A Bottle Of Already Frozen Breast Milk?

Layering frozen breast milk. How to add more breast milk to breast milk that is already frozen.
Can you add more to a bottle of already frozen breast milk?. Ceneri/E+/Getty Images

Is It Safe To Add More Breast Milk To A Bottle Of Already Frozen Breast Milk?

If you want to collect, freeze, and store your breast milk, but you're only getting a little bit of breast milk each time you pump, you may be wondering if you can combine these small amounts together. It would be convenient if you could combine, freeze, and store your breast milk in the amounts that your baby is taking at each feeding.

By putting small quantities of breast milk together into one container, you can also maximize the storage space in your freezer. But, is it safe?

You CANNOT Add Freshly Expressed Breast Milk To Frozen Breast Milk

Freshly expressed breast milk or even breast milk that has been pumped and left out at room temperature, is warm. Warm breast milk CANNOT be added to already frozen breast milk. If you add warm breast milk to frozen breast milk, the frozen breast milk will defrost a little bit. And, once your frozen breast milk begins to defrost, you should not refreeze it. It should be used right away or moved to the refrigerator and used within 24 hours. 

You CAN Add Refrigerated Breast Milk To Frozen Breast Milk

While you cannot add warm, freshly expressed breast milk to a container of frozen breast milk, you CAN safely add freshly pumped then cooled down, refrigerated, breast milk to frozen breast milk.

Adding more (cold) breast milk to already frozen breast milk is called layering. Layering can be done throughout the day until the storage bottle contains the amount of frozen breast milk that you would like it to have. Here are 5 tips for adding more breast milk to already frozen milk. 

5 Tips For Adding More Breast Milk To A Container Of Frozen Breast Milk

  1. You can add more breast milk to already frozen breast milk if you collect the breast milk on the same day, you have a healthy, full-term baby, and it's for your private use at home.

  1. Place your freshly pumped breast milk into the refrigerator and allow it to cool for 30 minutes to 1 hour before adding it to a container of frozen breast milk.  By refrigerating the breast milk first, it will help to prevent the already frozen breast milk from defrosting. 

  2. When adding the cold breast milk to a container of already frozen milk, the amount that you add should be less than the amount of the breast milk that is already frozen. This is another way to help to prevent the frozen milk from defrosting.

  3. You should pay attention to how much breast milk that you put into each container, and be careful not fill the storage container to the top. Your breast milk will expand as it freezes, so you need to leave some room at the top of the bottle to allow for that expansion. If your storage bottle is too full, it can burst in the freezer.

  4. When adding more breast milk to your containers, keep in mind how much breast milk your baby is taking at each feeding. It will help to reduce waste if you store your breast milk in 2, 3, or 4-ounce portions. You can always defrost another 2 to 4 ounces if necessary, but if you have breast milk stored in 6 or 8-ounce portions, you cannot refreeze what you don't use. You will have to throw away any leftover breast milk that has been thawed and warmed.

    You Should NOT Layer, Or Add Any Breast Milk, To Already Frozen Breast Milk If:

    You collect the breast milk on different days. Breast milk collected on different days should be kept separate. 

    You are pumping your breast milk to bring to the hospital. If your child is sick or premature and in the hospital, you should not open and close the storage bottle to add more breast milk. Each time you open and close the storage container, there is a risk of introducing germs and bacteria. This type of contamination is more dangerous for a sick or premature baby than it is for a healthy, full-term infant. So, once you seal the top of the collection bottle the first time, leave it closed until it's time to use it in the hospital.

    You are collecting breast milk to send to a milk bank. If you are sending your breast milk to a milk bank, follow the collection and storage guidelines that the milk bank provides.

    You think your recent pumping session could have been contaminated. If you are not in a clean environment, or you were not able to wash your hands before pumping, don't add the milk from that expression to a bottle of already collected breast milk. You don't want to contaminate the entire bottle that you worked hard so to collect. 

    Sources:

    Academy of Breastfeeding Medicine. Clinical Protocol #8: Human Milk Storage Information For Home Use For Healthy Full-Term Infants. 2004. Princeton Junction, New Jersey

    Lawrence, Ruth A., MD, Lawrence, Robert M., MD. Breastfeeding A Guide For The Medical Profession Seventh Edition.  Mosby. 2011.

    Neville, Margaret, ed. Lactation: Physiology, Nutrition, and Breast-Feeding. Springer Science & Business Media, 2013.

    Riordan, J., and Wambach, K. Breastfeeding and Human Lactation Fourth Edition. Jones and Bartlett Learning. 2014.

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