How to store, freeze and thaw breast milk safely

March 26, 2020

Whether you’re trying to build up a supply of stored breast milk for your return to work or stockpiling for occasional nights out, you’ll want to have a stash of breast milk in the freezer for safe-keeping. The whole process for pumping, storing, freezing and, later, thawing breast milk can appear complicated at first. It might seem like there are so many rules to follow, and the process might feel overwhelming at times. It’s common to have questions.

The good news is that all the work you put into pumping and freezing your milk has a fantastic payoff. As Dr. Florencia Segura, a pediatrician at Einstein Pediatrics explains, pumping and freezing your breast milk is highly advantageous for your child. “Whether breast milk is fresh or has been in the freezer for 9 months, we consider it ‘liquid gold,’” she says.

As the experts we interviewed explain, the process of collecting and storing your milk in the freezer isn’t nearly as tricky as you might expect, especially if you and your caregiver are equipped with smart, up-to-date information.

Is frozen breast milk as good as fresh?

Many breastfeeding mothers wonder whether their thawed frozen breast milk is healthy for their babies, especially as it compares to fresh breast milk. 

“Thawed frozen milk is good for your baby,” Dr. Snehal Doshi, a neonatologist with Millennium Neonatology, assures. Doshi explains that while giving your baby fresh breast milk may be the first choice, thawed frozen milk is certainly healthier for your baby than formula.

Segura concurs, adding, “While it is true that some of the anti-infective properties are lost when milk is frozen, any breast milk is ‘liquid gold’ in that it is customized for your baby and still helps protect babies from diseases and allergies,” says Segura. “Also, the risk of bacterial contamination of milk that has been refrigerated for too long instead of being frozen completely outweighs any downside of freezing milk."

How do you store breast milk in the freezer safely?

The first step in safely storing breast milk is to pump and collect the breast milk in a hygienic manner. “Wash your hands thoroughly before preparing breast milk,” Doshi suggests. Then, says Doshi, you should make sure to properly clean all your pump parts, as well as any storage bottles or containers you plan to use. You should also clean the counters where milk will be handled so that it doesn’t become contaminated. 

After that, Doshi suggests storing your milk as deeply into your freezer as possible. “Do not store breast milk in the door of the refrigerator or freezer,” he says. “This will help protect the breast milk from temperature changes from the door opening and closing.”

How long does breast milk last in the freezer?

One of the reasons so many moms choose to freeze their breast milk is because of how much longer it can be stored in the freezer than in the fridge.

While breast milk can be stored in the fridge for three to five days, says Segura, it can be stored in the freezer (at 0 degrees Fahrenheit) for up to nine months. “If you have a deep freezer (-4 degrees Fahrenheit or colder), it can be stored up to twelve months,” she adds.

Breast milk storage guidelines

Storage type


Good for


40 degrees F

3-5 days


0 degrees F

Up to 9 months

Deep freezer

-4 degrees F

Up to 12 months

Source: CDC

One tip Segura wants to make sure moms keep in mind: “Make sure your milk is labeled so you can use it before it ‘expires’ in 9 months.”

How do you thaw frozen breast milk safely?

OK, so you have an awesome stash of frozen milk, and you’re ready to use a bag or two. The question now is how do you thaw that frozen breast milk for your little one to drink.

There are several options for thawing frozen breast milk, according to Doshi:

  • Transfer it to the fridge and thaw it overnight.

  • Set it in a bowl or container of warm or lukewarm water to thaw.

  • Run it under lukewarm running water.

Do not microwave breast milk. “Never thaw or heat breast milk in a microwave,” Doshi warns. “Microwaving can destroy nutrients in breast milk and create hot spots, which can burn a baby’s mouth.”

How long is breast milk good for after it’s been frozen and thawed?

Sometimes you might find yourself with a bottle or freezer bag of thawed breast milk, but your baby isn’t quite ready to drink it. You might be wondering for how long that now-thawed milk will stay healthy and safe for your baby.

The answer is simple: If thawed breast milk isn’t going to be used right away, it should be refrigerated, says Segura. After that, it should be fed to your baby within 24 hours.

Easy hacks for freezing breast milk

Some of the best advice about pumping and freezing breast milk is from moms themselves. Juliana Parker, a mom of three breastfed babies and a 15+ year labor and delivery nurse from Mount Airy, Maryland, shares her top hacks for freezing breast milk. 

1. Have a power outage back-up plan

A few times in her years of pumping, Parker experienced power outages. “It was very stressful to have a freezer full of breast milk and to then lose power,” she shares. Her solution? “To help prevent loss, I would purchase dry ice whenever we had severe thunderstorm warnings. I also had a list of friends who were willing to provide backup freezer services for me in the case of a power outage.” 

2. Save space with storage bags

While some moms choose to freeze their milk in bottles, Parker found that using plastic breast milk storage bags was a smarter idea in terms of storage space. “I initially began storing my breast milk in bottles but found it took up too much space in my freezer,” she says, “so I switched to storage bags that I could flatten down.”

3. Use an ice cube tray

Bottles and plastic storage bags aren’t the only options for freezing milk. Parker found it helpful to store her milk in an ice cube tray with a lid. This way, she could store the milk in small amounts and not risk wasting milk. 

Even better, the breast milk ice cubes become useful once your baby starts teething. “When my children began teething, I would half fill some ice cube trays to create a smaller cube,” Parker offers. “I would then rub their gums with the small blocks of the frozen breast milk to help with their teething discomfort.”

With these steps — along with support from your healthcare provider, lactation consultant and fellow moms — you’ll be well on your way to freezer storage success. You’ve got this!

Tips and stories from parents and caregivers who’ve been there.

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