Thawed breast milk is good for how long

Reviewed by Dan Brennan, MD on July 20, 2022

If you have produced a surplus of breast milk or need to store breast milk for your child to drink while you’re away, storing it in the freezer might be your best option. Freezing breast milk is a safe, effective way to keep a backlog of milk on hand. However, you must be careful when thawing it. If you thaw it incorrectly, you could damage the milk or make it unsafe for your baby to drink.

Expressing Breast Milk

To freeze breast milk for later consumption, you’ll need to express it first. This can be done by hand or with a breast pump. Either way, it may take a little while for your milk to start flowing if you’re not relaxed or near your baby. Try winding down before expressing, keeping your baby or a picture of them close by, covering your breasts with a warm washcloth, or taking a warm bath or shower.

Storing Breast Milk

Once you’ve expressed the desired amount of milk, you’ll need to tackle breast milk storage. After washing your hands with soap and water, open a clean, sturdy plastic container or food-grade glass container meant for food. Anything that doesn’t contain the chemical bisphenol A, also known as BPA, is safe, including plastic bags designed to store milk.

Label each container of milk with the date that you expressed the breast milk and how much milk was expressed. Knowing how much milk is in each container will help you be more precise later on as you need to thaw specific amounts of breast milk. Put them in the back of your freezer or refrigerator — the temperature will be lowest in this spot. If you aren’t able to store them in one of these spots immediately, you can use a cooler with ice temporarily.

How Long Does Stored Breast Milk Last?

Depending on how you store it, your stored breast milk could last anywhere from a few hours to six months, depending on the quality of your freezer. Consider the following when deciding how to preserve your breast milk:

  • At room temperature, recently expressed breast milk can last up to six hours. If the location is warm, it’s recommended to use the milk within four hours to be sure it doesn’t spoil.
  • In an insulated cooler, freshly expressed milk can be stored alongside ice or ice packs for up to 24 hours.
  • In the refrigerator, fresh breast milk will stay good for up to four days. It’s recommended to use or freeze the milk within three days to be extra safe.
  • In a freezer, expressed milk can be used for up to six months. If possible, try to use the frozen milk within six months to be certain it’s still good.

Basic Tips for Thawing Frozen Breast Milk

Thawing breast milk is simple, but you must be sure to follow the correct steps to avoid ruining the milk. When you’re ready to defrost breast milk, consider the following tips:

  • Use the oldest milk available, unless there’s a reason to use more recently expressed milk. The composition of breast milk changes according to your baby’s needs, and newer milk might better nourish them in certain situations.
  • If possible, thaw breast milk by placing the frozen container in the refrigerator overnight or for several hours.
  • If you need to thaw the milk quickly, place the container of milk under warm running water. You can also fill a larger container with warm water and put the frozen container of breast milk in it.
  • Don’t use hot water or the microwave to thaw the breast milk. This could make the milk less nutritious for your baby and could end up being too hot for your baby’s mouth.
  • It’s natural for the breast milk to separate into a layer of fat on top of the rest of the milk. Swirl the bottle around, but don’t shake it too hard.
  • To avoid wasting any milk, freeze it in two- to four-ounce batches. This way, you can thaw only the amount that you need without defrosting more than your baby can drink in a few hours.
  • Unless you plan on using fresh breast milk within four days, freeze it immediately to avoid losing any.

These are the fundamentals of how to safely defrost breast milk. Keep in mind that you can feed your baby expressed breast milk cold if you don’t want to risk warming the liquid up too much.

Using Thawed Breast Milk

Once it's defrosted, you should use thawed breast milk fairly quickly. If it's thawed in the refrigerator, you should use it within 24 hours. If it's thawed to room temperature or warmer, you should use it within an hour or two. If there is thawed milk left after a feeding, you can still use it within two hours. Don’t refreeze breast milk after it has been defrosted!

Depending on your diet at the time you expressed the milk, your thawed milk might be a different color than your current supply of breast milk. Thawed milk can sometimes have a different smell and consistency than fresh breast milk, but it’s still safe to use. If the milk is spoiled, your baby will likely refuse the milk. If this is the case, try storing the milk for a shorter period.

Confidently Thaw Your Frozen Breast Milk

Your breast milk is a precious source of nutrients for your baby! Freezing and thawing extra milk is a great way to ensure you don’t waste any of your supply. If you need help learning how to express, store, or thaw your milk, reach out to a healthcare provider or provider who specializes in lactation. If you have any concerns about expressing your milk or milk that you’ve already expressed, get in touch with a professional immediately.