Everything you need to know about breast milk storage

There’s no reason to cry over spilled milk, but there are plenty of reasons to cry over breast milk that wasn’t stored properly. Not only did you work hard to pump that liquid gold but sour milk can also make your baby sick. Here are the basic breast milk storage guidelines that all parents should keep in mind.

The rule of thumb is that untouched, freshly-pumped breast milk can stay out at room temperature for four hours or less, says Deborah Campbell, a neonatologist at The Children’s Hospital at Montefiore in the Bronx, N.Y. If it’s been longer than four hours, you need to throw it out (sorry!). If you know you’re not going to use the milk during that timeframe and your baby hasn’t sipped from it yet, just stick it in the fridge.

According to the American Academy of Pediatrics’ breast milk storage guidelines, once you’ve put breast milk in the refrigerator, it can stay there for up to four days. It’s during this window the milk’s fat, digestive enzyme activity and anti-infection benefits are at their peak, adds Campbell. To keep the milk cold, be sure to store it on the bottom shelf at the back of the fridge, not in the door.

If you are hitting the road and need to bring along a bottle or bag of breast milk, you can pack it in an insulated cooler with an ice pack and it should be safe for up to 24 hours.

If you don’t plan on using the milk within the four days that it’s at its best in the fridge, you should freeze it within 24 hours of pumping. Breast milk is good for three to six months when stored in a freezer attached to a refrigerator. As with storing it in the fridge, the milk should be kept in the back of the freezer. If you have a deep freezer or chest freezer, you can freeze the milk for up to one year.

Breast milk storage bags are your best option. Choose two- or four-ounce storage bags and, if you plan on freezing the milk, be sure to leave a little room at the top of the bag because the milk will expand when it freezes.

Write the date you pumped on the bag so you’ll know when to throw it out. Don’t use disposable bottle liners or other types of plastic bags. If you’re afraid that the bags may tear, you can put them inside a plastic container with a lid. You should avoid any containers made with bisphenol A or S, but you can freeze breast milk in freezer-safe glass or BPA-free plastic containers. Wash all bottles with hot, soapy water beforehand (or in the dishwasher) and dry them well. Do not use chemical disinfectants.

Remember the mantra: First in, first out. Thaw the oldest breast milk first.

There are several ways to safely thaw your breast milk:

-Place it in the fridge overnight to thaw.

-Run the bottle under lukewarm water.

-Set the bottle in a container of warm or lukewarm water.

-Use a waterless bottle warmer.

If you thaw the breast milk in the fridge, use it within 24 hours, counting from when it’s completely thawed. Once milk is brought to room temperature, use it within two hours.

Whatever you do, do not thaw your breast milk in a microwave oven because it can thaw the milk unevenly and potentially burn your baby!

It’s also important to never refreeze breast milk after it’s been thawed.

Why does thawed breast milk smell and look different than fresh breast milk?

That’s normal. This happens when women produce breast milk that is high in an enzyme called lipase. While this enzyme helps digest the fat content in breast milk, it can also affect the smell and taste of both fresh and frozen milk (it usually makes it smell and taste metallic or soapy). Women often don’t realize that their breast milk is high in lipase until they freeze it because the changes to the milk take a few hours—or even a day—to take effect, so you probably wouldn’t notice the changes with fresh milk. If you’re concerned about your baby not wanting to drink the breast milk, talk to your doctor to find out about a process to help neutralize the enzyme and lessen the smell.