mother breastfeeding her baby
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Can Breast Milk Go Bad Inside Your Body? Lactations Consultants Explain

It’s normal to wonder.

by Cat Bowen and Ellen Schmidt
Originally Published: 

If you’re breastfeeding your baby, then you already know your breasts are pretty amazing. Filled with the world’s most nutritious food as if by magic, your breasts are, in fact, one of your super powers as a mom. But just because they can hold your baby’s food supply doesn’t mean there isn’t a lot of work on your part. For parents pumping or doing a combo of pumping and breastfeeding, concerns about breast milk spoiling inside your boobs can be a little confusing. Is there an expiration date for your body’s handmade liquid gold?

Can breast milk go bad inside of your body?

“Breast milk is a living organism, unlike the pasteurized cow’s milk that we purchase at the store. The living components in breast milk are constantly changing based on your baby’s needs and the lactating parent’s microbiome,” Heather O’Neal, a certified nurse-midwife and lactation consultant in West Virginia, tells Romper. These dynamic properties serve to protect the breast milk, as well as optimize the health of the infant eating the milk. “Good bacteria in the breast milk eliminates bad bacteria within the breast as well as outside of the breast in the form of pumped milk,” O’Neal adds. Well that’s a relief.

Another reason that moms sometimes worry about the freshness of breast milk is if they’ve pumped at some point and witnessed the separation of “foremilk and hindmilk” after it sits in the refrigerator for a few days, according to O’Neal. Not to worry, she says. “As your baby gets older and the time between feeds extends, there will be a separation of the components of breast milk within the breast, much like unpasteurized milk that sits in the refrigerator. This separation is completely normal and expected for milk that sits for a period of time. A gentle ‘swirl’ of the milk after heating will reconstitute the milky elements and make it look normal again.”

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Do be mindful of how you store pumped milk, though

However, you should note the length of time that breast milk can be stored in the fridge. The Centers for Disease Control and Prevention (CDC) recommended that breast milk only be stored for four at room temperature. Breast milk that's stored in the fridge, towards the back, at temperatures below 39 degrees Fahrenheit can be stored for a total of five days, according to the CDC.

Speaking of timing, however, try not to go too long between breastfeeding sessions. Breast tissue is designed to reabsorb milk when milk sits for too long, such as during the process of weaning. While the milk is safe to feed to your baby, it’s not safe for the mother to go for long periods of time, typically four hours or more, between some sort of expression for the mother. “This is because milk also serves as a flush for the breast tissue and its systems, and bacteria and yeast can travel into the tissue through the nipple, setting up things like mastitis and thrush infections,” explains Ashley Georgakopoulos, IBCLC and Motif Medical Lactation Director.

The body is a regenerating machine. While there are some things that can't be regenerated — like those brain cells you lost watching nine hours of Real Housewives as you cluster-fed your baby — most things in your body keep remaking themselves or healing from damage. So worry not, my lactating friends. The milk in your own personal udders lasts indefinitely. As long as you're producing it, it's safe to drink. However, that yogurt in the back of your fridge that you're eyeing? Do you even remember when you bought that?


Heather ONeal, a certified nurse-midwife and lactation consultant, Breastfeeding for Busy Moms

Ashley Georgakopoulos, IBCLC and Motif Medical Lactation Director

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