If you have a new baby, you might be choosing to feed your babies with breast milk. Most doctors prefer it to formula because it has the perfect amount of nutrients, it's gentler on your baby's digestive system, and it can be better absorbed by their body.
It's not always possible to breastfeed, so pumping is a great way to provide breast milk so others can help with bottle-feedings.
But how long can you use breast milk once you make a bottle? It depends on a few things, like when the milk was expressed or pumped and how it was stored.
Expressed Breast Milk
Expressed breast milk is any breast milk you've pumped or removed from your breast so you can store it for use later. It's basically removing breast milk without you're baby breastfeeding.
How to express breast milk
- Use your hands. Also called hand expression, you use your hands to squeeze or press the milk out of your breast. This process usually gets faster and easier with practice, and it may be more comfortable if you find pumping painful.
- Use a pump. Manual or electric machines can remove milk from your breasts for you. Many people use pumps, but it's a good idea to know how to express milk with your hands. There may be times when you can't use your pump. Before pumping breast milk, it's important to make sure your hands, any pump parts, and collection containers are clean.
When to express your milk
- If you want extra breast milk for storage
- When your baby is sleeping
- To get milk out of your breast right when you wake up
- To keep up with pumping at work
- To release milk so it's easier for your baby to latch on
If you're away from your baby and you're regularly breastfeeding, try to keep the same schedule when you express your breast milk as you would if you were feeding. That sends a signal to your body that it should keep producing breast milk.
Storing Breast Milk
Depending on your baby's feeding schedule, you can store breast milk in different ways, and it can last several months. There are guidelines for how long the milk can be safely consumed.
Generally speaking, breast milk is good for:
- 4 hours when freshly expressed
- 4 days in the back of your refrigerator
- 6-12 months in a deep freezer
At room temperature (up to 77 F), breast milk will stay safe for your baby for up to 4 hours. Ideally, your breast milk should be kept as cool as possible. Experts recommend you keep it covered with a clean, cool towel to make sure it doesn't get contaminated. If your baby takes part of the breast milk, you should use the rest or throw it away within 2 hours.
How long is breast milk good for in the fridge?
Breast milk is safe in your refrigerator (around 40 F) for up to 4 days, and it's best to chill it right after it's expressed to maximize the time it's safe. Don't store it in the door of your fridge because the temperature there fluctuates from the opening and closing.
Breast milk in the freezer
If you don't plan to use the breast milk within 4 days, it's best to freeze it. Remember that the milk will expand as it freezes, so don't overfill the bags or containers. Freeze it in amounts of 2-4 ounces because that's what your baby can eat in one feeding, and you'll avoid wasting it. Be sure to mark the date that you collected the milk, too, so you can defrost the oldest milk first so it doesn't expire.
Breast milk storage bags
These are bags made specifically for storing and freezing expressed breast milk. They're different from the plastic bags you use for general household things. Never store breast milk in bags that aren't designed for breast milk.
Breast milk storage bags are bisphenol A (BPA)-free and generally considered safe. But researchers have found that microplastics (which have also been found in human breast milk) can seep into breast milk from the bags. More research is needed to know what that means for the health of your baby.
Breast milk storage bottles
Like breast milk storage bags, you can buy bottles that are made specifically for storing breast milk. You can also keep expressed milk in clean food grade glass or plastic containers with tight-fitting lids. But you shouldn't use disposable bottle liners to store your milk. Never store breast milk in plastic bottles with the recycle symbol 7 on them. These may have BPA in them, too.
Once you express your breast milk into a storage bottle or bag, label them with the date you expressed the milk. Write your baby's name on the label if it's going to a child care facility or another child care provider.
How to Warm Breast Milk
You can safely feed your baby breast milk that's cold or room temperature. Give it a try when you first start bottle-feeding to see if they like it that way. Babies often prefer warm breast milk because it's similar in temperature to the milk that comes from your breast.
If your baby prefers warm milk, use a bottle warmer to heat it up. This is safer than warming your milk on the stove or in a microwave because bottle warmers are specifically designed to warm it to a consistent temperature.
Test the warmth of your milk on the back of your hand before you give the bottle to your baby. If it feels too warm on your wrist, it's too warm for your baby's mouth. Let it cool until it feels OK on your skin.
Can warmed breast milk be refrigerated again?
Once you've taken breast milk out of the fridge or freezer and either warmed it up or allowed it to come to room temperature, use it within 2 hours. It's not safe to use breast milk that's been left out longer than that, and you should get rid of it if it has.
Don't put leftover breast milk back in the fridge to use later or refreeze it.
It's important to follow safety guidelines for breast milk because bacteria can grow in it if you leave it out for too long. Babies are more vulnerable to germs and may not be able to fight off illness or infection because their immune systems haven't had the chance to build up antibodies that keep them from getting sick.
How to Thaw Breast Milk
You can store expressed breast milk in a deep freezer for up to 12 months. Though, try to use it within 6 months if you can. And thaw the oldest batch first. Breast milk quality can go down over time.
To safely thaw breast milk, you can:
- Put it in the refrigerator overnight.
- Set the frozen milk in container with warm water.
- Run lukewarm water over it.
Don't thaw frozen milk in the microwave or quickly on the stove.
Once it's defrosted, swirl the milk around as some of the fats may have separated. This is completely normal and doesn't mean the milk has gone bad.
How long is breast milk good for after thawing?
You can use refrigerated breast milk for up to 24 hours after you thaw it. Keep in mind the countdown starts as soon as the milk is completely thawed and not from the moment you take it out of the freezer.
How to Tell If Breast Milk Is Bad
It's normal for breast milk to separate and have a yellow, orange, blue, or green tint to it. But it's a good idea to taste it before you give it to your baby. It's probably fine if it smells OK to you and tastes a little sweet. But you should toss it if there's a sour odor or flavor.
To make sure your breast milk is safe, you can:
- Smell and taste it every few hours once it's in the refrigerator.
- Thaw a batch each week to test.
Some people find that their breast milk tastes or smells soapy, metallic, or fishy. That doesn't always mean it's soured or spoiled, but you should talk to your doctor or lactation specialist about what to do if your breast milk tastes or smells bad or your baby doesn't like it. You may need to avoid certain foods, change how you pump or store your milk, or make other lifestyle changes.
Other Considerations for Giving Breast Milk Bottles
There's a misconception that you can't bond with your baby as well when bottle-feeding them expressed milk instead of feeding them directly from your breast.
How to bond with your baby
Hold your baby close when you give bottles and make eye contact while feeding. Talk to them with a soft voice as another way to enhance the bonding experience of feeding.
Offering breast milk in bottles allows everyone in your family an opportunity to establish connections. Encourage everybody, including siblings, grandparents, and cousins, to join in feedings so they can build bonds. Your baby will feel more closely connected with each member of your family. This will ease the pain associated with your absence if and when you return to work.