How Long Can Breast Milk Sit Out? Answers You Can Trust


Knowing that breast milk is your baby’s super food, you want to make sure its safe for them to eat. The question is, how long can breast milk sit out? Moms work to create and express this most nutritious golden milk. As moms, we schedule pumping time, drink supplements and eat food that increases milk supply. We even need to allow time to relax and keep the milk flowing. However, sometimes breast milk gets spoiled, and all those efforts go to waste. (Anyone who says "don't cry over spilled milk has never knocked over a hard-won 2.8 ounces after setting it down to wash the pump.)

It was not so long ago when I had to pump milk for my baby since he already started solids. Our pediatrician recommended adding milk to all of my baby’s mashed food. His mashed bananas, potatoes, and avocados were all prepared with my milk. However, it was only possible for me to pump in the morning. So, I'd keep those little bags to make his food. I am not one of those Moms on Instagram that has a refrigerator full of expressed or pumped milk or those Moms going viral filling 4-ounce storage bags with ease. But, my milk supply was adequate for my baby’s needs.

I remember when I first started expressing milk and stored it in the refrigerator. Around 8 days after I stored it, I went to use it again, and I noticed that the consistency was different. I had warmed it already, and then I opened it, and smelled it. It smelled different, too. I would never give my baby spoiled milk, so I decided to taste it. Indeed, that sour flavor gave away the spoiled milk.

How Long Can Breast Milk Sit Out?


All moms want the best for their child, but wise moms want to avoid wasting milk as well. In any case, breast milk shouldn't be fed to our children once spoiled. May it be hand expressed milk or pumped milk, you need to know how long breast milk sits out safely in various conditions -- such as at room temperature, in the refrigerator, and frozen among others. These are important to take note of to know if your expressed milk is still as fresh as you think it is. So, here is the answer to your question - how long can breast milk sit out? Note that the following are general guidelines in storing expressed milk for a healthy full-term baby. Also, the assumption is that moms expressed their milk under clean conditions - clean pumps and proper expression technique.

1. Freshly expressed breast milk at room temperature

Freshly expressed breast milk is best compared to refrigerated or frozen milk since it contains the highest in antioxidants, vitamins, protein, fat, and healthy probiotic bacteria. It may sit out for 4 hours at temperatures 72 to 79 degrees. It may even last for up to eight hours for temperatures 66 to 72 degrees. Since warmer temperatures lead to a faster rate of bacteria growth in stored milk, the maximum storage for expressed milk at room temperature is three to four hours.

Breast milk also contains vitamin C that depreciates over time. For example, freshly pumped milk at 73.4 degrees has 1.6 milligrams of vitamin C per 100 milligrams milk. 8 hours later, the vitamin C content is only at 1.0 milligrams per 100 milligrams.

2. Expressed breast milk in a cooler with ice packs

Sometimes, you need to transport your expressed milk so you could run some errands, or to get it home from work. These moments call for coolers with ice packs or specialized breast milk freezing and storage coolers with ice gels. At 59 degrees, freshly pumped milk lasts for up to twenty-four hours. Parents or guardians should transport expressed milk in a cooler to keep it chilled. Otherwise, you must carry the milk frozen. Note that upon arrival in your destination, milk must be used right away, stored in the refrigerator, or frozen.

Minimal bacterial growth was reported in a study conducted by Hamosh et al. on "Breastfeeding and the working mother." Once again, however, vitamin C content depreciates over time. Expressed milk in a cooler at 42 degrees 2.2 milligrams of vitamin C per 100 milligrams of milk. After 24 hours, the number drops to 1.7 milligrams of vitamin C per.

3. Refrigerated breast milk

A more effective way of prolonging the life of your freshly expressed milk is to refrigerate it. Chilled breast milk lasts for up to 8 days. At 39.2 degrees, bacterial growth is even lower. The bactericidal capacity of refrigerated milk, as well as changes in the milk composition, are low. Studies show that immunologic factors  in breast milk, such as IgA, cytokines, and growth factors, are not diminished with refrigeration for two days. Furthermore, experts say osmolality, bacterial counts, concentrations of IgA, lactoferrin and total fat exhibit no remarkable changes in four days. However, further research suggests milk's pH, white blood cell count and protein concentration decreased after four days.

Keep in mind that due to the frequent door opening, milk composition changes faster, as the refrigerator's temperature might not be reaching 39.2 degrees. It is best to store milk at the back of the refrigerator, as far from the door as possible.

4. Frozen breast milk

Placing your milk in the freezer right after expression prolongs the life of your breast milk the most. Experts recommend three months storage time in freezers within a typical home refrigerator. In a two-door freezer at 0 degrees Fahrenheit, milk lasts for three to four months. Breast milk could last up to twelve months in a deep freezer although up to six months is optimal. Experts prescribe freezing at 0 degrees Fahrenheit keep frozen food safe from contamination.

The composition of milk changes through time. Its fat, protein, and calories decrease after having been frozen for three months. Research also shows that there is a notable decrease in vitamin C levels after one to five months of storage. After six months, cytokines, IgA and growth factors from colostrum are steady while after nine months macronutrients, osmolality, and immunoactive proteins are constant.

5. Thawed breast milk after being frozen

You must thaw breast milk wholly and accurately. In thawing previously frozen breast milk, you need to place the milk in a container with cold or warm water or make it run in cold or warm water. You may also let it sit out in the refrigerator for 24 hours. At a temperature of 77 degrees or colder, breast milk sits out for up to 2 hours. On the other hand, thawed breast milk in the refrigerator sits out for up to 24 hours. Research indicates that thawed breast milk, frozen for at least six weeks at -4 degrees or cooler is similar to freshly expressed milk when it comes to bacterial viability. Experts suggest using leftover milk from feeding within a 2-hour period.

6. Re-heated breast milk

Experts do not recommend heating breast milk as it can be served cold or room temperature. Breast milk easily adapts to room temperature, so even pediatricians do not recommend heating. Breast milk's nutrients when re-heated may die, thereby losing its edge against formula milk. Too much heat inactivates milk’s proteins and decreases its fat. Experts also discourage heating in a microwave. Heat in the microwave is uncontrollable and may cause hot spots. However, if you decide to re-heat your milk, it can sit out only until feeding ends at room temperature, or up to 4 hours if left in the refrigerator.

Breast Milk Expression, Handling and Storage Guidelines

breastfeeding her baby

Mothers express milk because they will either be away for a while, they want to maintain adequate milk supply, or they want to mix breast milk with their baby's food. You need to properly handle breast milk since this is your baby's super food. We've provided a list of tips and guidelines for you on breast milk expression and storage.

Breast milk expression

Sometimes we forget some necessary steps in expressing breast milk. First of all, do not forget to sanitize all breast pump equipment, tubes, and storage bottles before you use them. Make sure they are all dry and kept in a clean place. Before pumping, wash your hands with soap and water; if not available, alcohol with at least 60 percent concentration will do, like hand sanitizer.

A helpful tip in pumping milk is to pump in early mornings as milk-making hormone levels increase at this time. Also, pump both breasts at once as you'll produce milk more quickly.

Breast milk storage

Proper breast milk storage plays an essential role in making shelf life of your breast milk reach its maximum. To start with, make sure you store your breast milk in specialized containers made for breast milk. Make sure it is BPA-free! Afterward, label your breast milk with the date and time you collected it, amount or volume, and name if your baby is in childcare. Leave your breast milk in an area where there would be no damage in your storage containers or bags.

It is better to store milk in small amounts of about three to five ounces. Storing in these amounts lessens milk wastage. You need to leave space in your container because milk expands as it freezes. In doing this, you allow the breast milk to expand without breaking out of your bag or bottle.

There are ways to preserve the freshness of your milk. You may begin by separating your milk from food, especially fish, seafood and meat. It may affect the freshness of your milk and may hasten bacteria to grow in your milk. Some suggest putting your milk in a separate container. Afterward, position your breast milk as far as possible from the door of the refrigerator or freezer, so the milk does not spoil quickly every time the freezer door opens. Follow the first-in, first-out method; thereby, the first milk to be stored, the first to come out.

Breast milk handling

There are also guidelines for proper thawing. Begin by thawing milk entirely and adequately. To make your milk warm, you may place it in running warm water or in a container with warm water. You also need to swirl your storage bag or container gently after thawing to mix the fat with the rest of the milk as it may have separated. Remember not to shake the milk!

Some additional reminders include placing your milk in the freezer immediately if milk is not to be used within four days and never re-freeze milk after thawing.

​How to Tell if Breast Milk is Bad

Babies reject spoiled milk - thanks to their gagging reflex to strange taste. However, as parents, we do not even want to get close to the point of giving spoiled milk to our children. You may not be able to detect that breast milk is already bad if you just took it out of the freezer but once thawed, you'll start seeing the difference. Appearance, smell and taste of breast milk changes when it spoils.

To start with, you need to properly thaw the breast milk and swirl your container as suggested in the guidelines above. Once completed, inspect your breast milk. Your milk may initially separate into layers as fat separated from the other contents of the milk. However, after some swirling, everything must be mixed. If you spot chunks, clumps or substances not mixing after swirling, it's time to dispose of the milk. Likewise, if the milk is too thick and pus-like, you should not feed it to your baby.

Secondly, like any other food, a foul odor tells you breast milk is spoiled. Upon opening the container, you may already smell the rancid and sour smell. Sometimes it may not be that apparent so you may need to smell it a little closer. One would have gut feels about the odor, throw that milk away.

Lastly, your suspicions would be validated if you taste it. Some get weirded out by this tip; however, it is the fastest way to tell if your milk has gone bad. Spoiled milk would have a sour taste similar to that of spoiled cow's milk. In actuality, it will taste a bit more pungent, and one droplet will make you feel like vomiting.

However, if you have doubts that milk may have gone bad, such as knowing it sat out on the counter for over 3 hours, we suggest you follow your intuition. When in doubt, toss it out. A baby never got sick from milk they didn't drink.

​​​​Breast Milk in a Wrap

At the end of the day, we do not want to have to inspect our breast milk to know whether it is spoiled or not. We do not want to see all our effort and time go to waste with all those storage bags ending in the trash. Therefore, it is best to practice proper breast milk expression, handling, and storage.

As we have mentioned above, always keep in mind a clean environment when expressing milk. Take note of the number of hours, days or months on how long breast milk can sit out. Remember to store your breast milk appropriately. So, moms -- no more asking "How long can breast milk sit out?" -- now you know.

Last update on 2021-05-20 at 15:38 / Affiliate links / Images from Amazon Product Advertising API


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