Breast Milk Storage after Pumping


Given the complications and busyness of modern life, expressing breastmilk for storage has become increasingly common. Particularly after maternity leave as women re-enter the workforce, it is common for them to pump and store their breastmilk. How you store breastmilk, however, depends on how you want to use it and when.


What Types Of Containers Should You Use To Store Breastmilk?

There are two common ways to store breastmilk: bottle and bag. More specifically, most women will choose to store breastmilk either in a plastic or glass bottle, or in a sterile, sealable bag. These will then get placed into the refrigerator or the freezer, where they will remain until used for feeding.


How Much Breastmilk Should You Store In Each Container?

It is recommended that most women only store the amount of breastmilk that they are going to use in a given feeding session. For instance, if your baby consumes roughly five ounces of breastmilk during a given feeding session, you should store that amount in each container. In general, most women will need to store milk in small quantities between one and five ounces. This is particularly important if you are freezing breastmilk, as it does not make sense to unthaw breastmilk and store it again.

How Long Can Breastmilk Be Stored?

It is important that breastmilk does not go bad and lose the many health benefits it provides. Because of this, there are many guidelines for the storage of breastmilk, particularly with respect to breastmilk storage time. There is also a difference between expressed breastmilk storage and pumped breastmilk storage.

How To Store Breastmilk? – Storage Guidelines

The following guidelines apply for how to store breastmilk at home in both refrigerated and frozen environments:

  • You can store your breastmilk at room temperature (up to 25 degrees Celsius) for a maximum of four hours.
  • At temperatures below four degrees Celsius), you can store breastmilk in the fridge for up to 24 hours. In colder climates or regions, breastmilk can sometimes remain in the refrigerator for three to five days, but in hot climates, the opening and closing of refrigerator doors makes longer storage more difficult.
  • In smaller refrigerators with only a freezer compartment, it is recommended to keep breastmilk for only two weeks.
  • In an insulated cooler or box filled with ice-packs (such as the one you might transport to and from work), you should only keep breastmilk stored for a maximum of 24 hours.
  • In a freezer (temperatures of around -18 degrees Celsius), breastmilk can generally be stored for three to six months, taking into account the opening and closing of the freezer and the climate you are located in.

Table 1: Breast Milk Storage Chart

Freshly expressed milk
Warm room 80-90°F/27-32°C Up to 4 hours
Room temperature 61-79°F/16-26°C Up to 8 hours
(less is better)
Insulated cooler with ice packs 59°F/15°C Up to 24 hours
Refrigerated milk (Store away from door)
Refrigerator (fresh milk) 32-39°F/0-4°C Up to 8 days
(under 3 days is best)
Refrigerator (thawed milk) 32-39°F / 0-4°C Up to 24 hours
Frozen milk (Store at back, away from door)
Freezer compartment of small refrigerator Varies Up to 2 weeks
Self-contained freezer unit of a refrigerator/freezer <39°F / <4°C Up to 6 months
Separate deep freeze 0°F / -18°C Up to 12 months
(6 months ideal)


How To Freeze Breastmilk?

Breastmilk should be frozen as soon as possible after it has been expressed, and stored at temperatures of around -18 degrees Celsius.

The following rules and recommendations apply for breastmilk that is being frozen:

  • If you are freezing the milk, leave some space at the top of the bag, since frozen milk will often expand during freezing.
  • Never store the breastmilk uncovered, and make sure that bags or bottles are sealed tightly.
  • Frozen, stored milk will often separate, so when it is removed just make sure to give a little shake to get it to mix back together again once it has been taken out of storage.
  • Store frozen milk at the back of the freezer; this will minimize contact with outside temperatures and allow the milk to be frozen for the longest period possible.

How Can You Thaw Frozen Breastmilk?

To thaw breastmilk, you should keep the breastmilk in the refrigerator and let it sit for around 12 hours. This is usually best done overnight and in advance of the day where you will need to feed your baby, given the time involved in the thawing process.

The following rules and recommendations apply to the thawing of breastmilk:

  • You should avoid, whenever possible, leaving the breastmilk out at room temperatures to thaw.
  • Never refreeze breastmilk that has already been thawed.
  • For faster thawing, it is acceptable to keep the breastmilk under hot water and slowly increase the temperature as means of thawing.
  • Never attempt to put the breastmilk on the stove or in the microwave as a means to thaw the milk.


How To Warm Breastmilk?

To warm breastmilk, you should place it in a container of hot water where it can absorb heat from some of the surrounding liquid. First, heat up the water, that you are going to use, in a small container. Then, place the container of frozen milk in the container to warm up.

The following rules and recommendations apply for the thawing of breastmilk:

  • If you just want to heat up the milk for your child’s consumption, try using a bottle warmer.
  • Never heat up breastmilk by placing it on the stove or in the microwave.
  • You should not try to store again breastmilk which has been already warmed.

How To Store Thawed Breastmilk?

Thawed breastmilk should be stored in the refrigerator, as it is usually best to keep the milk at cooler temperatures at all times.

  • Milk that has thawed in the refrigerator should only be kept there for a maximum of 24 hours after thawing has completed. (This will usually mean 36 hours after you first place from the freezer into the refrigerator to thaw.)
  • You should not attempt to refreeze thawed breastmilk.
  • Only thaw as much breastmilk as your child will consume during a given day, otherwise, it will likely go bad (and it will not be as fresh).

What About the Taste And Odour Of Thawed Breastmilk?

Breastmilk has generally not gone bad unless it tastes sour or smells particularly bad. Most children will not notice smell or odour, and they would react more to a sour taste than to smell. Some milk will specifically go bad because of lipase, a normal breastmilk enzyme that some mothers will produce in higher quantities than others. When thawed, this can cause the breastmilk to smell rancid or soapy, but this will often go unnoticed by infants (though some will refuse to drink it). Changes in the smell and odour of breastmilk can also be the result of changes in the mother’s diet or health (such as through medications, diet, drinking or smoking).

How Can You Store Breastmilk At Work?

You can store breastmilk at work by refrigerating it in sealed containers and then transporting it to your home in small coolers that are refrigerated with ice packs. You should always make sure to clearly label it, both so that it is easier to store when you get home, and so that it is not confused if in public storage. You should always try to store transported breastmilk as soon as possible after arriving home.

Can You Add Fresh Expressed Breast Milk To Stored Frozen Breast Milk?

You can add recently expressed breastmilk to frozen or refrigerated milk, but only if you expressed it earlier in the same day. Nevertheless, you should cool the expressed breastmilk before adding it to frozen or chilled breastmilk that you had already expressed. You should never add warm breastmilk to frozen milk, as this will cause it to thaw and affect its lifespan.

More Storage Tips

The following are some other general tips for the storage and use of breastmilk:

  • Breastmilk can vary in colour. Some milk will appear bluish, yellowish, or sometimes even brownish.
  • It is normal for breastmilk to separate (with the fatty cream often moving towards the top. Give it a small shake to get it to mix back together.
  • You should smell the milk before feeding it your baby; if it smells particularly bad, you should not give it to them.
  • Always consider exactly how much breastmilk you will need and store accordingly.
  • Make sure to label everything so that you do not waste breastmilk or use milk on different days (thus leading to the possibility of spoiling).

Breastmilk storage is an important reality of life for modern mothers, particularly those in the workplace. While it can be a complicated and time-consuming process, mothers should take care to ensure breastmilk is stored correctly and safely. There are many guidelines for how to do this, and they depend on the method of storage, the location of the storage unit and how much breastmilk you are storing. Paying attention to these conditions will allow the breastmilk to be kept for the longest amount of time possible, and allow for no degradation in quality for your child.

Also read: Most Common Breastfeeding Problems & Their Solutions