• Catrina M.P.

Breast Milk Storage and Feeding Tips

Updated: Sep 8, 2020

As if learning to properly express breast milk wasn’t enough, education about storage is equally important. Many of us may have heard of the “4-4-4 rule” or some use “6-6-6” instead. The numbers refer to the amount of hours breast milk can be safely stored at room temperature, the amount of days in the refrigerator and the amount of months in the freezer.

So, which is correct? Maybe both. Maybe neither. 

Here are the recommended storage guidelines:

Freshly expressed breast milk can stay out on the counter at a cool room temperature for 6-8 hours if collected under very clean conditions (2).

Breast milk can be stored in the fridge for 5-8 days also if collected under very clean conditions (2). Labeling the bottles with the date and time will help you to stay organized. You can create labels easily by writing on masking tape with a pen and sticking it on the bottle or  simply use an erasable marker to write directly on the bottle. 

You can store breast milk in a freezer for 6-12 months based on the type of freezer that is being used as well as the conditions under which the milk was collected (2). It is best to store breast milk in the back where it stays cooler rather than in the front or on a door. Filling containers to the top should also be avoided as the breast milk will expand once frozen. Also, if using storage bags, place them down flat in the freezer rather than standing up in order to allow for more storage space. Thawed milk should never be refrozen, and should be used within 24 hours after being defrosted.

link listed in references
Image from the Medela website (2)

More to Consider

Another thing to be mindful of is the ever changing components of our magical, living human milk. Breast milk changes not only over the days, weeks, months and years in order to adapt to your child’s needs, but it also changes throughout each day and even functions as a sleep aid. Due to the change in hormones, it has been suggested to feed your baby milk expressed at night during the night and the same applies for the day time in order to maintain the circadian rhythm (1). 

If ever in doubt, the advice of following the 4-4-4 rule is easy to remember and is safe for almost all breastfeeding parents. The 6-6-6 rule is appropriate for most families who practice good hygiene, keep a cool enough room temperature in the home and store expressed milk properly and towards the back of refrigerators or freezers. 

It is important not to mix the methods of storage. In other words, it is best to do 1 of the 3 options without combining them (store on the counter, in the refrigerator or in the freezer). Avoid keeping fresh milk out for a few hours then refrigerating it. Likewise, do not put expressed milk in the freezer after it has been refrigerated for several days.

If you plan on being away from your child and want to know how much breast milk to leave, keep in mind that the average baby will usually drink between 2-4 ounces of milk per feeding. The amount of breast milk a child takes at each feeding usually depends on how often he or she feeds. Therefore, if you nurse your child at least 12 times a day, it is likely he or she will take an average of 2 ounces per feeding. Also remember these numbers are averages and since our babies rarely take the same amount of milk at each feed, the amount may be higher or lower.

Heating Breast Milk

If you wish to heat expressed breast milk that has been stored prior to feeding, it should be done by putting the bottle or container in warm or hot water or using a bottle warmer machine. Breast milk should never be heated in a microwave. A gentle “swish” of the bottle once heated rather than shaking it aggressively is all that is needed before a feeding.

It is not recommended to reheat breast milk or use the same bottle from an earlier feeding at a later feeding as the milk will be considered “contaminated” after an hour or so. Therefore, it is advised to discard whatever milk was not taken at a feeding, unless your baby consumes it within the next hour. This is another reason why it’s ideal to begin storing 1 or 2 ounces of expressed breast milk per container because you can always heat up more if you need to and you won’t waste any milk.

Another use for any leftover milk is to use it on your baby’s skin! Simply rub it in as a lotion or use it in a bath. 

Feeding Tips

Another helpful point for bottle-feeding is to store the milk in the same bottles you’ll be feeding with. Doing this simple step saves you time and money as you will not have to transfer milk into various containers, you avoid the struggle of getting the fat off the sides of the bottle during the transfer, and you will have less of a clean-up afterwards.

You may wish to avoid nipple preference and stay away from artificial nipples when feeding your baby your expressed breast milk until breastfeeding is well established. Introducing bottles and pacifiers may affect the latch and consequently the breastfeeding relationship, especially with younger infants. Other feeding methods include: cup, syringe or spoon. A supplemental nursing system (SNS) or lactation aid, may be most ideal for supplementing in cases when parents wish to exclusively feed at the breast but supply is low or milk is not being transferred adequately.

If bottle-feeding is right for your family, there are certain steps you can take to help maintain your breastfeeding relationship. Always use the slowest flow nipple and take frequent pauses to mimic what the baby does at the breast. Also be mindful of positioning: the baby should be sitting more upright and the bottle should be held more horizontally. Finally, enjoy frequent skin-to-skin contact as much as possible with your baby.

My mother feeding our newborn

Storing one ounce at a time in the beginning, then adding an ounce as needed as your baby grows and perhaps feeds less often will ensure your milk is rarely wasted. You can always prepare more if needed!

You can also keep a bottle or two of freshly expressed milk ready to use on the counter whenever necessary if you plan to feed your baby expressed milk at least once a day. Remember that expressed breast milk can always stay out at room temperature for 4-6 hours or more.

When, Where and How to Store Breast Milk

This all depends on each unique situation.

You can start to freeze your breast milk when you have enough stored in the fridge. For example, you may mainly store expressed milk on the counter and use that, but like to keep at least one bottle in the fridge per day. If a time comes in which you’ll need more milk stored in the refrigerator for any reason, you can start adding bottles and maybe keeping up to 5 bottles at a time in the fridge. Then once you hit 5 (or whatever number is best for you), you can start storing in the freezer to build a stash.

Can I combine two separate containers of stored milk?

The answer is usually yes.

You can combine stored milk of the same temperature. For example, if you have two containers in the refrigerator each with an ounce of milk in them, you can combine the two ounces into one container and then reheat it (or not) and feed it to your baby. You can combine stored milk that was expressed on different days as long as the milk is not spoiled. Fresh milk that has been stored at room temperature should not be combined with refrigerated or thawed milk.


  1. Breast Milk's Circadian Rhythms. (2018, May 25). Retrieved from https://www.llli.org/breast-milks-circadian-rhythms-2/

  2. Medela AG. (2018, April 18). How to store, freeze and thaw breast milk. Retrieved from https://www.medela.com/breastfeeding/mums-journey/storing-and-thawing-breast-milk

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