You've put in the pumping time to build up a little freezer stash of breast milk (great job!) and now you're ready to pull some out for your baby. So what's the best way to turn the icy clump back into liquid gold for your little one to drink?
Gradual gentle thawing is generally the way to go, say the experts.
"Breast milk should be defrosted slowly to ensure you're preserving the milk's nutritional and immunological properties," says Suzanne Chan, D.N.P., C.L.C., C.P.S.T., a pediatric nurse practitioner and certified lactation counselor at the Infant Cardiac NICU at NewYork-Presbyterian Morgan Stanley Children's Hospital in New York and a member of the What to Expect Medical Review Board.
Here are some tips for defrosting breast milk.
Put frozen breast milk in the fridge overnight
If you know your baby won't need the milk until the next day, you can simply stick the baggie(s) in the refrigerator and let it thaw overnight, says the Centers for Disease Control and Prevention (CDC). [1] (It's a good idea to pop them in a bowl or container to catch any rogue leaks.)
The milk might still be a little slushy or icy the next day, especially if you reach for it first thing in the morning. No worries if that's the case - you can still get a bottle together within a few minutes.
"I always did it the night before (so about 10-12ish hours), and they would be like half-thawed in the morning," reports What to Expect Community member giirlmama. “Cold water would thaw the rest of it fairly quickly.”
After transferring the fully thawed milk into your baby's bottle, give the milk a gentle swirl to re-mix it. (Sometimes the fatty part of the milk can separate from the watery part when it sits.)
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From there, you can warm the milk if your baby prefers it that way. But if she’s happy to take the milk cold or at room temperature, that's okay too.
Defrost the milk in warm water
When you can't plan for an overnight thaw and need milk quickly, stick the baggie(s) in a bowl of lukewarm water, the American Academy of Pediatrics (AAP) recommends. [2] (Make sure they're completely sealed so water doesn't get into the milk.)
Depending on how much milk you're defrosting, it should thaw within 15 to 30 minutes, Chan says.
And here's a trick for speeding the process along: "Every few minutes, add new water because the frozen milk will lower the temp of the water, thus slowing down the thawing process," recommends What to Expect Community mom osc0313.
Once the milk is defrosting, you can add it to the bottle, swirl it, and (if you'd like), warm it before giving it to your baby.
Use a bottle warmer
Defrosting with a bottle warmer isn't on the list of recommended thawing methods from the CDC or the AAP. But if you've got one, it's another option that can take your milk from frozen to warm within five to 10 minutes, depending on the temperature setting and recommendation of the specific bottle warmer, says Chan.
Some parents have concerns about this method, since heat can potentially cause microplastics in the storage baggies to leach into the breast milk. If you're uncomfortable with that possibility, this option might not be for you.
Alternatively, you can talk about the pros and cons with your baby's pediatrician to decide whether defrosting with a bottle warmer might be okay in moderation.
Safety tips for handling frozen breast milk
You've put a lot of effort into making, pumping, and storing all that extra milk. To ensure it stays fresh and nutrient-rich once you pull it from the freezer, keep these tips in mind:
Never microwave breast milk. The intense heat of the microwave destroys your milk's nutrients. Plus, it can create hot spots that could burn your baby's mouth.
Grab the oldest frozen milk first. Frozen milk is best within six months, but it's safe to use for up to 12 months. Try to get into the habit of putting a date on every bag of pumped milk and so you can easily reach for the milk that's been in the freezer for the longest. "If your baby is showing aversion to frozen milk, try mixing some of your oldest frozen milk with freshly collected milk," says Chan. "It's natural for a mother's milk to change in composition and taste, and adapt to the baby's needs as they grow."
Try to thaw just what you'll need. It'll help you avoid waste, since you can't re-freeze thawed milk. If it seems like you're going to have some extra (but it's still within the window of freshness), you can add it to your baby's bath, suggests What to Expect Community mom shadowkatts43. Some research suggests it may be soothing for your baby's skin.
Use thawed milk in a timely manner. If you thawed your milk in the fridge, use it within 24 hours from when it's completely thawed (not from when you put the frozen bag in the fridge). Once the milk is at room temperature, use it within two hours.
Watch for any signs of spoilage. Some color variations can be normal. But a sour smell, stringy or clumpy texture, or your baby refusing the milk are all signs that it may have gone bad, Chan says. Toss it!
When you need to defrost breast milk, the easiest options are to thaw it overnight in the fridge or put it in a bowl of lukewarm water. Steer clear of microwaving, even when you're in a rush. It's bad for the milk and it could hurt your baby's mouth.
You should defrost breast milk gradually to preserve its nutrients. Thaw it overnight in the fridge or place it in a bowl of lukewarm water.
Never microwave breast milk. It can destroy the milk's nutrients and potentially burn your baby's mouth.
Defrosting with a bottle warmer may be okay in moderation, but talk with your baby's pediatrician if you have concerns.
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