Breastmilk Storage and Handling Guidelines


Guidelines for the storage of handling of breastmilk are different than for formula (artificial baby milk) and other infant foods. Live cells and other protective factors in breastmilk inhibit the growth of bacteria, increasing shelf life. Scientific research has lead experts in the creation of guidelines for safe storage and quality preservation of breastmilk. Please note that the guidelines below apply to healthy, full term babies. If your baby is premature, hospitalized, or ill check with your health care provider for specific storage and handling recommendations.

Breastmilk Storage Guidelines

Before Expressing Your Milk

  • Wash your hands thoroughly with soap and warm, running water.
  • Assure all items that will come in contact with your milk have been washed in hot, soapy water and rinsed well (or washed in a dishwasher). This includes your pump parts, storage container, lids, caps, etc. Exception: breastmilk storage bags

General Storage Guidelines

  • Label expressed milk with the date. If your baby goes to group day care, also label with his name.
  • Use the oldest milk first.
  • Breastmilk can be be stored in any food grade container with a tight fitting lid (examples: plastic or glass baby bottle with storage lid or disk, hard plastic freezer box).  Choose BPA-free plastics.
  • Disposable breastmilk storage bags are a space saving option, and are convenient when access to water for washing is hard to come by. Avoid storing in disposable baby bottle liners and plastic sandwich bags as these pose a greater risk of tearing and leaking.
  • Store in amounts of 2-4 oz (average amount a breastfed baby takes per feeding). This will reduce waste and make for quicker milk warming. Consider freezing a few containers of your milk in 1-2 oz quantities in case a little extra is ever needed.
  • Remember that breastfed babies need less total ounces of breastmilk than formula fed babies do of formula. The average daily intake of an exclusively breastfed baby from age 1-6 months is 25 oz.

How to Store

  • If breastmilk will be used at the next feeding and the room is not above 77 degrees F, store at room temperature.
  • If you’re collecting milk over the course of a day and you do not have access to a refrigerator, store it in a cooler bag with ice packs until you get home.
  • If breastmilk will be used within a few days, store in the refrigerator.
  • Freeze milk you’ll be storing for longer than a few days.

Storing in a Cooler Bag

  • You can hold freshly expressed milk in a cooler bag (soft sided cooler, or small plastic cooler) with ice packs for up to 24 hours.
  • Choose a cooler bag that is well insulated.
  • Line the cooler bag with frozen “blue ice” style reusable ice packs.

Storing in the Refrigerator

  • Best when you plan to use milk within a few days; breastmilk can be stored in the refrigerator for 2-8 days. Most experts recommend to refrigerate for 3 days or less.
  • Store in the coldest area refrigerator, usually the top shelf.
  • Avoid storing in the door of the refrigerator, which experiences the greatest temperature fluctuations.
  • Consider placing a box of baking soda in your refrigerator to reduce refrigerator odors. This will help prevent your milk from absorbing odors and flavors from other foods.

Storing in the Freezer

  • You can store your milk in a separate door refrigerator freezer for 3-4 months.
  • You can store in a deep freezer for 6-12 months.
  • Liquids expand as they freeze. Fill containers no more than 2/3 full.
  • Cap containers loosely until milk is fully frozen, then tighten. This allows air to escape as the freezing milk expands.
  • If using breastmilk storage bags, squeeze out the air before sealing. Freeze lying flat. Frozen bags then become like tiles that you can easily stack, or even “file” in a plastic shoebox.
  • Store in the back of the freezer, away from the door. If the freezer is self-defrosting, avoid storing along the floor or the sides, as well. This will help avoid partial defrosting due to temperature changes and better preserve the quality of your milk.
  • Wondering if your freezer is cold enough? Check your ice cream. If it is frozen hard and is difficult to scoop, your freezer is at an optimal temperature.

Warming Breastmilk

  • Breastmilk may be thawed in the refrigerator overnight or quickly thawed under warm, running water.
  • Breastmilk may be warmed under a faucet of warm, running water or in a container of warm water (such as a large cup or small cooking pot).
  • Before feeding to baby, gently swirl heated milk to mix it back together then sprinkle a few drops on your inner wrist to check the temperature.
  • Do not heat breastmilk directly on the stove.
  • Do not heat breastmilk in a microwave. Hot spots in the milk can cause burns. Heating in a microwave also destroys some of the anti-infective properties of breastmilk.

Frequently Asked Questions

My breastmilk looks nothing like the milk I buy at the store. What is breastmilk supposed to look like?

Breastmilk can have a blue, yellow, or even a brown tint. The color of breastmilk can vary according to when the milk is pumped (milk may appear thinner and bluer when the breast is very “full”), and even what mom has ate or drank. For example, breastmilk may appear pink if a mother drinks an orange soda. Breastmilk can appear watery or creamy, and anything in between. All of these variations are completely normal.

Breastmilk is not homogenized like cows milk from the grocery store. When expressed breastmilk is left sitting for a while, it separates into a milk and a cream layer and the cream rises to the top of the container. Before feeding your baby, simply swirl the warmed milk gently (rotate the container in a circular motion) to mix the layers back together.

With all these normal variations, you may wonder how you will know if your milk is spoiled. The short answer is you will know! Breastmilk that has spoiled has an unmistakable odor, similar to that of soured cows milk.

Can I mix milk from different expressions?

Yes! Always label the milk with the date of the oldest of the two. For example, if you express on March 1st and combine that withe milk you express on March 2nd, label the milk as March 1st. Freshly expressed milk can be added directly to refrigerated milk. If adding fresh milk to frozen, cool it in the refrigerator first. To avoid partial defrosting, assure that there is less fresh milk than frozen.

Can I reheat breastmilk that my baby didn’t eat?

The safety of this practice is unknown. Most experts say it would be reasonable to discard 1-2 hours after feeding. Please see the following article for more information:
The Safety of Reusing Expressed Breastmilk

Can I refreeze breastmilk?

The most widely accepted recommendation is that fully thawed breastmilk must be used within 24 hours or discarded.

USDA food safety guidelines suggest that if a food is still partially frozen (slushy, with visible ice crystals), it can be refrozen. Some experts recommend mothers follow this advice with their frozen breastmilk, assuring that they use the refrozen portions as soon as possible. Be sure to check with your health care provider before refreezing partially thawed milk for your baby.

Interestingly, a 2006 study by Rechtman et al looked at the effects of freezing and thawing on unpasteurized donor milk. The results showed that human milk was more robust than previously thought and thawing and refreezing had remarkably few effects on the milk. However, there is not yet enough evidence to change breastmilk storage guidelines to reflect their findings. The current recommendation remains to discard thawed milk after 24 hours.

Can I freeze milk that has been refrigerated?

Sometimes mothers store milk in the refrigerator expecting to use it in the next few days, only to find that it is not needed. If your milk has been in the refrigerator for 3 days or less and it still smells fresh, some experts suggest you may freeze it for longer storage. Label this milk with the date it was expressed and a reminder to use it as soon as possible.

Can I save breastmilk that has been mixed with formula for the next feeding?

No. Breastmilk that has been mixed with formula must be discarded after a feeding.

Exclusive breastfeeding is important to the health of your baby.  In most circumstances, babies don’t need anything other than breastmilk for the first 6 months of life.  If you need or choose to supplement with formula, one solution is to offer any available breastmilk first. When your baby has finished your milk,  then offer formula. If he doesn’t finish the supplement, your milk will not be wasted along with it.

If your doctor prescribes mixing formula and breastmilk together, discuss how to mix and store safely.

My milk smells funny when it’s thawed. Is it bad?

Not necessarily. Milk can smell different after it’s been thawed. Please see Why is my baby refusing my stored breastmilk? for more details.

Can I store my milk in the common refrigerator at my workplace?

Yes. According to the Occupational Health and Safety Administration (OSHA), “contact with breast milk does not constitute occupational exposure“.

Furthermore, the Centers for Disease Control and Prevention (CDC) reports “CDC does not list human breast milk as a body fluid for which most healthcare personnel should use special handling precautions. Occupational exposure to human breast milk has not been shown to lead to transmission of HIV or HBV infection. However, because human breast milk has been implicated in transmitting HIV from mother to infant, gloves may be worn as a precaution by health care workers who are frequently exposed to breast milk (e.g., persons working in human milk banks).”

If the possibility of co-workers handling your milk without your knowledge concerns you, consider storing your milk containers in a sealed bag  in the refrigerator or even in a separate area of the refrigerator (a drawer, for example). Some moms prefer to store their milk in a cooler carrier that they can keep near their work area.

Can I save milk that has been expressed while I have thrush?

You can save the milk and use it while you and your baby are being treated. Yeast spores do not die when frozen. It is unknown whether or not milk that has been frozen during a Candida infection will cause reinfection, but it is theoretically possible. The current recommendation is to clearly label the milk that you are expressing during treatment, and always use that milk first while being treated. If there is any of the expressed milk left once your treatment is completed and the thrush infection is cleared, discard it.


The Academy of Breastfeeding Medicine Protocol Committee (2010)  ABM Clinical Protocol #8: Human Milk Storage Information for Home Use for Full-Term Infants Breastfeeding Medicine, 5(3) 127-130

Hamosh, M. et al (1996) Breastfeeding and the Working Mother: Effect of Time and Temperature of Short-term Storage on Proteolysis, Lipolysis, and Bacterial Growth in Milk Pediatrics 97(4), 492-498

Kent, J.C.  et al (2006) Volume and Frequency of Breastfeedings and Fat Content of Breast Milk Throughout the Day Pediatrics, 117(3), 387-395

Mohrbacher, N (2010) Breastfeeding Answers Made Simple: A Guide for Helping Mothers Amarillo, Texas. Hale Publishing, L.P.

Rechtman, D.J. et al (2006) Effect of environmental conditions on unpasteurized donor human milk Breastfeeding Medicine, 1(1), 24-26

Wilson-Clay, B., Hoover. K (2005) The Breastfeeding Atlas Manchaca, Texas. LactNews Press

© Native Mothering–All Rights Reserved

Updated 2/25/13

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