Breast Milk Storage and Handling

When you feed your baby breast milk, you are feeding them a living substance filled with nutrients, enzymes and immune properties. This is true whether you nurse your baby directly or give them a bottle of breast milk.

The process of safely pumping, storing, and warming milk might seem a little daunting. While you do need to take some steps to keep the process clean and create a plan for feeding, most parents are able to get into a routine that becomes second nature.

Here is a guide to safely storing and handling breast milk that can answer some of your questions and give you some tips on getting started.

Composition of Breast Milk

What is it that makes breast milk such an amazing substance and perfect food for your baby? The answer lies in the complex and ever-changing mixture of nutrients and living organisms that your body tailors to meet your baby’s needs.

Here are just a few of the nutrients contained in breast milk:

  • Fats
  • Proteins
  • Carbohydrates
  • Vitamins
  • Minerals
  • Immunological Factors
  • Enzymes
  • Antioxidants

By handling and storing your breast milk with care, you are helping to ensure your baby gets the greatest amount of nutrients possible.

Breast Milk Storage and Handling

Hygiene, Preparation and Cleaning

No matter how hard you try, you will never be able to completely eliminate bacteria from your skin, breast pump or feeding equipment. Even though that might sound a little frightening, don’t panic just yet.

The good news is that most of the bacteria your baby will be exposed to from drinking a properly cleaned bottle of breast milk isn’t harmful at all, and taking a few simple steps can help significantly reduce the total amount of bacteria present. Additionally, the breast milk itself contains immune factors that will help fight off some of the remaining germs.

What Can a Mother Do to Keep Expression as Clean as Possible?

While you don’t need to put yourself under unnecessary stress, you should do your best to make pumping a clean process.

Fortunately, some planning ahead and a little effort will go a long way toward helping you achieve that goal.

Use a Brand New Pump.

Any breast pump supplied by insurance or bought at a store has an exclusive single-user design. While you are able to clean and sanitize the outer parts of the pump, some internal parts cannot be cleaned and could pass bacteria from one user to another. Even if it was given to you by a friend or family member, you should never use a breast pump that has already been used by someone else. The exceptions to this rule are pumps that you can rent from a hospital. These professional-grade models can be fully disassembled and the hospital has the proper equipment to sterilize the pump between users.

The high cost of certain electric models can discourage some women from buying a new pump. However, insurance companies and Medicaid are required by law to cover basic pumps. Your doctor’s office should be able to help you determine which pump models are covered under your plan.

Practice Good Hand Washing and Hygiene.

Washing your hands well with soap and warm water before pumping or handing any milk is one of the best ways you can help keep the process clean. If you don’t have access to a sink, use an alcohol-based hand sanitizing gel.

While some people may say you need to wash your breasts off before each pumping session, this is not necessary. Regular showers or baths should be enough to keep your breasts clean under normal, everyday circumstances. However, if you are using any soothing creams or ointments on your nipples, you may need to wash them off before pumping. While many of these products are safe to use while nursing or pumping, be sure to follow the package directions.

Keep Your Pumping Area Organized and Clean.

  • Keep everything you need for pumping in a clean and easily-accessible spot.
  • Gather all your pumping supplies before you begin and lay them out. This can help you avoid a last-minute search for a small piece and potentially contaminating your hands or other equipment.
  • Keep your pumping/expressing area free of old food or drinks.

Make Sure Other Caregivers Know How to Safely Handle and Feed Milk.

If your partner or babysitter will be feeding your baby a bottle, make sure they know the proper techniques for warming milk and cleaning bottles.

It may help to have a detailed list of steps that other caregivers can reference. Make sure to include where they can find all the necessary clean pieces, soap for washing and where they should put the clean bottle pieces.

Cleaning and Sanitizing Your Pump and Containers

Reading the instruction manual’s detailed cleaning directions for sanitizing and cleaning your pump can be enough to make any parent feel a little overwhelmed. While the description may sound complicated, the actual process is much simpler and is likely to quickly become part of your daily routine.

Completely Disassemble all Parts. To ensure every part is cleaned well, you will need to work with each individual piece. Make sure to fully take apart all bottles, nipples, rings and pump components.

Some bottle or pump parts can be very small, and it can be easy to mistake two small pieces as one larger piece. Check the manufacturer’s instructions to make sure you fully disassemble each component. Many instruction manuals will include photos or illustrations of each of the individual pump parts.

Immediately Rinse all Pumping Supplies That Have Contact With Breast Milk. Thoroughly rinse all the bottles and pump parts in lukewarm or cool water as soon as possible after pumping or feeding. This can help reduce the chances of milk drying onto the parts and becoming difficult to remove later.

Every pump model is different, but here are some examples of common parts that are likely to have direct contact with milk and will need to be washed and sanitized:

  • Breast shields
  • Any suction valve assemblies
  • Pump collection bottles
  • Bottle caps and rings
  • Feeding Bottles
  • Nipples

Unless your pump is not functioning correctly, the tubing should not have contact with milk and does not need to be washed or sanitized.

You may need to leave your tubing open to the air or use the pump to run air through the tube. Check your pump’s instruction book to determine what the manufacturer recommends for your model.

Wash all Bottle and Pump Parts. Wash each part thoroughly with dish soap and warm water after every use.

You can also use a scrubbing brush designed for bottles and nipples, but it is not necessary as long as you clean all your pieces right away. You can also use specialized soaps that are designed to break down breast milk residue.

Some pump parts and bottles can be cleaned in the top rack of your dishwasher. Check the instruction manual to see if your model’s parts are dishwasher safe.

Pre-packaged cleaning wipes are also available for purchase. These wipes will not replace regular washing, but they can be helpful if you have to pump away from home.

Sanitize According to the Manufacturer’s Instructions. A sterilized surface is one that has no organisms on it. According to the Food and Drug Administration, no home methods of sterilizing will actually eliminate all organisms.

Fortunately, sterile bottles and pump parts are not necessary in most cases. Pieces that are clean and sanitary are sufficient when handling and storing milk for healthy, full-term babies. If your baby was premature or has a health condition, always carefully follow the cleaning directions your baby’s doctor gives you.

Sanitizing procedures can vary from manufacturer to manufacturer and even model to model, so be sure to follow the instructions provided for your specific model.

Most pump parts will need to be sanitized daily if you use your pump every day, or sanitized after each use if you pump less frequently.

There are a few different sanitizing methods you can use:

  • Boiling water. Submerge the pump components and bottles in a boiling water bath for the amount of time recommended by the manufacturer, typically five to ten minutes. Remove the pan from heat and use tongs to carefully take each piece out of the water.
  • Microwave. You can purchase pouches that are designed to steam-sanitize pump parts, bottles, nipples and pacifiers. Add a small amount of water to the bottom of the pouch, place the dirty items inside and seal the pouch shut. Microwave the pouch for the recommended amount of time, usually a few minutes. Carefully remove the pouch from the microwave and allow some of the steam to escape before carefully removing the clean pieces.
  • Cold Water Sanitizing. This method uses sanitizing tablets dissolved in water to create a soaking solution. Fill a food-safe bowl with cool water, add a tablet and allow it to dissolve. Submerge all your pump parts or bottles and allow them to soak for the time recommended on the tablet package. This method can be a great option if you are away from home and are unable to use a microwave or boiling water.

Designate a Clean Area for Air-Drying Sterilized Pump Parts and Containers. After washing or sanitizing, make sure to drain out any retained water. Choose a clean area, and lay your pump parts or containers out in a single layer to dry on a clean towel or rack.

Air-drying your bottle and pump parts allows you to handle your clean pieces as little as possible and helps minimize the bacterial transfer that hand-drying could cause.

Store Clean, Dry Bottle and Pump Parts in a Closed Container. If you do not plan to use your pump again within the day, store your pieces in a clean place.

Storing wet parts could lead to mildew growth, so make sure all pieces are completely air-dried. Wash your hands well before carefully placing each piece into a clean, lidded container. Store your contained parts away from heat sources and out of direct sunlight.

Expressing Milk

Read your pump’s instruction manual and make sure you understand how to use your model before you begin to pump. Improper use or poor positioning can lead to pain, plugged ducts or mastitis.

Always wash your hands thoroughly before expressing milk by pump or hand.

Pump Expression

  • Manual Pumps. These handheld pumps are lightweight and compact. Although they will certainly work for daily use, manual pumps take more time than an electric model and can require a fair amount of energy from you. Assemble the pump and place it on your breast according to the manufacturer’s directions for your specific model. Most manual pumps use a pull handle or a squeeze bulb to create suction. The pump will draw milk out of your breast each time you squeeze the handle or bulb. Pump until you have reached your desired amount of milk or your breasts are empty.
  • Electric Pumps. Electric pumps come in single or double styles to pump one or both of your breasts at the same time. Some women find using an electric pump more comfortable than a manual one. Assemble the pump and follow the manufacturer’s instructions to place it on your breast correctly. Turn the pump on and set your desired suction pressure. Pump until you have collected your desired amount of milk or your breasts are empty.

Hand Expression

Breast pumps use negative pressure to draw milk out of your breast, while hand expression uses positive pressure to push the milk out.

Hand expression can be a good solution if you don’t plan to feed your baby a bottle frequently, you don’t want to invest in a pump or if you want to express just a small amount of milk. Once you learn the proper technique, expressing milk by hand is easy. However, it is almost always a very time-consuming job, and it can also be physically taxing.

Situate a clean bottle so the opening is next to your nipple. Place your thumb on one side of your breast and your fingers on the other, about one inch away from your nipple on either side. Squeeze your fingers together and gently pull on your breast at the same time. You should get a stream of milk with each repetition.

Storing Milk

How Does Storage Effect Milk?

Feeding your baby directly from the breast provides the highest amount of nutrients and is most ideal. However, there are a host of reasons why that may not be possible for many moms, especially in today’s busy culture.

Numerous studies have been done over many years to assess how well breast milk holds up under storage. Many nutrients are unchanged or only slightly altered by storage, while others are more delicate and may lose some of their potency. Most studies conclude that longer storage times usually result in lower nutrient levels.

Here are just a few of the ways certain nutrients can be altered when stored in the refrigerator or freezer.

Vitamins. Researchers compared Vitamin C and Vitamin E levels in breast milk that had been freshly pumped, refrigerated for 96 hours or frozen for one year at both normal and ultra-freeze temperatures.

Vitamin E levels remained the same in all categories. However, the Vitamin C levels decreased in all the stored samples, and the samples frozen for the longest times had the lowest measured levels.

Fats. The freezing process often breaks the chemical bonds between fat and the liquid part of milk, causing the fat to separate and rise to the top of the container when the milk is thawed. While this separation itself does not affect nutrition, a separate study found that longer frozen storage times resulted in decreased fat concentration.

Protein. The protein lactoferrin may be instrumental in helping your baby absorb higher amounts of iron and is also important for inhibiting bacterial growth in the digestive tract.

Lactoferrin appears to tolerate refrigeration well, and the protein levels decrease only slightly when the milk is frozen.

However, heat can destroy lactoferrin along with several other vital nutrients contained in breast milk. Thaw your milk slowly and warm bottles gently to preserve the highest amounts of lactoferrin.

Enzymes. Breast milk contains the enzyme lipase, which works to break down fats into a more easily-digestible form.

Some mothers may find that thawed milk has a different color, odor and texture than fresh or refrigerated milk. Thawed milk may smell soap-like or slightly sour. These changes are due to lipase’s action on fats.

The longer you leave your milk on the counter or in the refrigerator before freezing it, the stronger these changes seem to be. The amount of time the milk is frozen also seems to make the changes more pronounced.

Even though the color or smell might be a little off-putting, this milk is safe to feed your baby. However, some babies may dislike the smell or taste and refuse to drink it.

To reduce the effects of lipase, use your frozen milk as soon as possible. Additionally, place any milk you plan to freeze in the freezer immediately.

Antioxidants and Immunological Properties. According to a study published by The Journal of Maternal-Fetal and Neonatal Medicine, the total levels of antioxidants in mature breast milk fell by half when the milk had been refrigerated for three days, and decreased by half again when the milk had been frozen for two weeks.

The same study found that levels of the immune cell interleukin-10 were unchanged by refrigeration or freezing. In fact, milk that has been refrigerated for eight days has been shown to have lower levels of bacterial growth freshly pumped milk. This is due to the milk’s immune cells actively destroying bacteria during the storage time.

It is important to keep in mind that even if refrigerated or frozen milk may have lost some of its nutritional power, your breast milk is still a healthy and perfect food for your baby. Never feel guilty about feeding your baby safely stored milk.

Milk Storage Containers

Only use containers that are food-grade and designed specifically to hold breast milk. Avoid storing your milk in regular plastic zip-top baggies or single-use bottle liner bags.

Bisphenol A (BPA) Concerns

BPA is a chemical substance commonly found in plastic items of all kinds. It has been shown to have negative health effects, primarily in disrupting delicate hormone balances.

It is generally recommended that you do your best to avoid BPA in any item that your baby will use. If you choose to use plastic storage bags or bottles, look for products that are labeled BPA-free.

There are several options for storing your milk in the refrigerator or the freezer, and each one has both positive and negative aspects.

Plastic Breast Milk Storage Bags

These bags are designed specifically to hold breast milk and have secure zip tops to minimize leaks. Ounces and partial ounces are clearly marked and make it easy for you to measure how much milk you put into the bag. Designated spaces allow you to record the date and amount of milk.

Many bags have a self-standing construction. When you pour milk in, the weight of the milk will cause the bag to stand independently.

Bags are the most space-efficient way to store your milk in a freezer. Lay them flat to freeze, then arrange the frozen bags in a stack or upright in a container.


  • Storage bags have a simple design that is easy to use.
  • Bags come in a variety of package sizes and are readily available in stores and online.
  • You have a couple of different options for organizing frozen bags, and they take up less space.
  • The disposable design makes storage bags a convenient choice.


  • Other items in the freezer could damage a plastic bag, and this can lead to leaks when thawing.
  • Though it’s rare, possible defects in the side seams or zipper top could cause leakage.
  • Storage bags are a single-use item and could be expensive, especially if you pump and store daily.
  • The disposable design generates plastic waste.

We have reviewed some of the best breastmilk storage bags available on the market.

Plastic bottles

Plastic bottles offer several benefits: they are sturdier than plastic bags, are easy to find for purchase and cost less than most glass bottles. All bottles, whether they are plastic or glass, are a little bulkier than bags and take up more storage space.

Many breast pumps come with plastic collection bottles, and these can also double as storage bottles. There are also several brands of plastic bottles readily available in stores or online.

If you want to freeze in a plastic bottle, make sure the brand you choose has an airtight cap. You should be able to tell from the package if a bottle is freezer safe.


  • A bottle is stronger than a bag and is very unlikely to leak.
  • Your breast pump may include plastic bottles that you can use both to pump and store milk.
  • Plastic bottles are less expensive and less likely to break than glass.


  • Bottles take up more space.
  • If you plan to freeze a large amount of milk, you mill need many bottles.
  • Bottles require more effort than bags. They will need to be washed with every use and sanitized regularly.

Glass bottles

If you want to avoid plastic products, glass bottles could be an ideal choice for you.

Glass bottles could have a slight safety advantage since bacteria often have a harder time growing on the glass due to its non-porous surface.

Not all glass can be frozen. If you plan to freeze your glass bottles, look closely at the package label to ensure you are buying a freezer-safe product.

Thawing or warming milk in a glass bottle will need to be done very gently and slowly. Any sudden temperature changes could cause your bottle to crack or shatter, so be sure to allow for extra time.


  • Glass bottles are eco-friendly and do not contribute to plastic waste.
  • A glass surface is better at inhibiting bacterial growth.


  • A glass bottle is delicate and could break. You will need to handle it with care.
  • Since glass is fragile, it will require more time to thaw and warm.
  • Glass bottles are the most expensive option.

Sanitizing Storage Containers

Storage Bags. These containers come pre-sterilized by the manufacturer. You can simply open the bag and use it immediately.

Since there is no way to sanitize storage bags, they are a strictly single-use item. Never attempt to wash a bag and re-use it. Throw out each bag as soon as you empty it.

Plastic and Glass Bottles. Follow the manufacturer’s instructions for sanitizing your bottle before the first use. For everyday cleaning, use the same procedures that you would when washing and sanitizing pump parts. See details in the “Cleaning and Sanitizing Your Pump and Containers” section above.

How to Label and Fill Milk Storage Containers

Always handle all clean storage containers with thoroughly washed hands.

Label all containers clearly. A storage bag is usually easiest to write on before you put any milk in it.

If you are storing your milk in a plastic or glass bottle, use a piece of water-resistant paper tape or a label. Write with a pen or marker that has water-proof ink.

Be sure to include the following information of every label:

  • Date the milk was pumped.
  • The number of ounces in the container.
  • Your child’s name if they are in daycare or will be with other children who take bottles.

Filling Bags. Label the bag appropriately, and fill the bag with your desired amount of milk. Carefully squeeze out any excess air and secure the bag shut. Never fill the bag past the maximum fill line. When milk freezes, it expands and an overfilled bag could break.

Filling Bottles. Pour the desired amount of milk into the bottle and secure the lid. If you are using your bottle to freeze milk, don’t fill it more than about three-quarters full; a full bottle could burst since the milk will expand as it freezes. Label the bottle appropriately.

Frequently Asked Questions and Storage Tips

How Long Can You Store Breast Milk?

Countertop. Milk that has been freshly pumped and not previously refrigerated can safely sit at room temperature for several hours.

The temperature of the individual room directly affects how long you should let your milk sit out.

  • In rooms that are 80-90°F, refrigerate or use the milk within four hours.
  • In rooms that are 61-79°F, milk can sit out for up to eight hours, but using or refrigerating it within four hours is best

Insulated Cooler Bag or on Ice. Milk will stay fresh for up to 24 hours. Keep the bag closed as much as possible to minimize cold loss.

Refrigerator. Always store milk in the coldest part of the refrigerator, which is typically at the very back. Even though it may be easiest to set or take the milk from the refrigerator door, this is the worst spot to place it. Opening the door frequently can cause the storage temperature to fluctuate widely, and the door is usually farthest away from the cooling element.

  • Freshly-pumped milk can be refrigerated for up to eight days, but using or freezing the milk within three days is best.
  • Use Thawed milk within 24 hours after thawing is complete.

Freezer. Always store milk in the coldest part of the freezer. If you have a freezer compartment, put your milk at the very back and never store it in the freezer door. If you have a chest freezer, place your milk at the very bottom.

The type of freezer you have will determine how long you can store frozen milk.

  • Freezer compartment. For small freezer sections contained within a refrigerator, frozen milk can be stored for two weeks. Freezer compartments that have their own separate door can be used for longer, up to six months.
  • Chest freezer. You can safely store milk in a deep freezer for up to 12 months, though using the milk within six months is ideal.

How Much Milk Should You Freeze at a Time?

Even though seeing those milk containers filled to the top can also fill you with well-deserved pride, it is usually best to freeze milk in smaller amounts. Doing this will cut down on thawing time and will also minimize waste by allowing you to tailor the amount you thaw to what your baby can drink at a time.

For babies one month of age and older, freezing about 3 to 5 ounces in each container is the most common recommendation.

Just after birth, babies will typically take about a teaspoon of milk per feeding, but their stomach capacity will rapidly increase during the first month. From the ages of one month to six months, most babies will take about 2.5 to 5 ounces of milk at each feeding.

Is it Safe to Add Freshly-Pumped Milk to a Container of Stored Milk?

You can safely add new milk to a container of stored milk as long as you follow some simple guidelines:

  • Ideally, milk in one container should all be from the same day. However, you can add new milk to an existing container within two to three days. If your container has milk from more than one day, write the date the oldest milk was pumped on the label.
  • Allow the new milk to cook thoroughly before adding it to an existing container. Warm milk may cause the temperature of the stored milk to rise to an unsafe level.
  • The amount of new milk added to a container of frozen milk must be less than the frozen amount. For example: If you have 3 ounces of frozen milk, you must add less than 3 ounces of new milk to the container.

Is it Safe to Freeze Refrigerated Milk?

Milk will stay fresh in the refrigerator for up to eight days, and you can freeze the milk at any point during this time.

Follow the same procedure you would when freezing freshly-pumped milk. Label the freezer container with the date the milk was pumped, not the date you placed it into the freezer.

What do You do With Leftover Milk?

If your baby decides that they are full with an ounce of milk left in their bottle, you may find it tempting to save the leftovers for your baby’s next meal. After all, breast milk contains some pretty amazing bacteria-fighting properties.

However, while the antibacterial factor is proven, there have been no studies done to determine the safety of feeding your baby leftover milk. The current guidelines state that you should throw out any milk left after a feeding.

How Soon Should You Use Thawed Milk?

Thawed milk is safe to feed to your baby for up to 24 hours after it has completely thawed.

If your baby does not finish the entire bottle of previously frozen milk at the feeding, treat it like leftover refrigerated milk and throw it out.

Can Thawed Milk be Re-Frozen?

Since freezing kills some of the milk’s immune cells, thawed milk is more susceptible to bacterial growth than fresh or refrigerated milk.

It is never safe to re-freeze milk. Throw out any milk that has been thawed for more than 24 hours.

How do You Re-Mix Separated Milk?

Breast milk contains a high amount of fat. The freezing and thawing process can cause the fat to rise, and two distinctly visible layers will form in the container.

Your first instinct may be to give the bottle or bag a good shake to mix the fat back in, but a vigorous motion could actually harm some of the delicate elements that make your milk so healthy.

Instead of shaking, hold the top of the container and softy swirl it or turn it over to gently re-combine the milk.

How Can You Determine if Expressed Milk Has Gone Bad?

Breast milk that has been frozen and thawed could have a slightly different color, smell and consistency than fresh or refrigerated milk. This is perfectly normal and the milk is safe to feed to your baby.

It’s likely that you will know right away if your milk has truly gone bad. Spoiled milk will have a distinctly strong odor and sour taste, and you should throw it out immediately.

Organization Tips

Always use the oldest milk first – Milk will eventually go bad and nutrition decreases with longer storage times. Make sure you use the oldest containers of milk first to help avoid waste.

Develop an organization system that works for you – Setting up a system that allows you to easily rotate your milk containers by date can prevent you from overlooking old milk and can also save time in the long run.

  • Refrigerated storage bags and bottles1. Arrange the containers by date in a straight line at the back of the refrigerator, with the oldest milk placed in the front and the newest milk placed in the back.2. Take the container with the oldest milk from the front of the line every time you feed your baby.3. Each time you pump, place the new milk at the very back of the line.
  • Frozen storage bags1. Use a small, narrow box or a small plastic bin to organize your bags upright by date.2. Arrange the bags by date with the oldest milk in the front and the newest in the back.3. Follow the same process outlined above to efficiently rotate your milk.
  • Frozen bottles1. Make sure the date on each bottle is clearly visible and has not become faded or discolored from the cold temperature.2. Place a few bottles of milk that have been pumped at about the same time in small boxes.3. Clearly label the boxes with the dates the milk was pumped, then rotate the boxes by date and use the oldest bottle in the box first.

Feeding Refrigerated Milk

How to Warm a Bottle of Milk

All milk that has been refrigerated or thawed needs to stay in cool storage until you are ready to feed your baby.

Bringing your baby’s milk up to a palatable temperature is easy and only takes a few minutes. Your goal is to gently warm the milk to roughly body temperature, not heat the milk to steaming.

You have a few options to accomplish the task:

Submerge the Bottle in a Bowl of Warm Water – Place your baby’s bottle in a container of heated water for several minutes. You can warm a bowl of water either on the stovetop or in the microwave. You can also use a bowl of warm tap water.

A cold glass bottle that has just come out of the refrigerator could crack or shatter when submerged in warm water. Run the cold bottle under a stream of tepid water for a couple of minutes before placing it into the bowl of slightly warm water. After a few minutes, replace that water with fresh water that is a little bit warmer. Repeat this process until your milk is the desired temperature.

Hold the Bottle Under Warm Running Water – Hold your baby’s bottle under a stream of warm water and slowly rotate the bottle to expose different areas to the heat. Due to the fact that you are moving the bottle and mixing the warmed milk into the cold, this warm-water method typically works faster than submerging the bottle.

Use an Electric Bottle Warmer – These small devices hold a wide variety of bottle sizes. The internal heating element works quickly to bring your baby’s milk to a comfortable temperature either at home or on the go.

  • Countertop Bottle Warmers. These compact appliances have an easy-to-use design and take only a few minutes to heat your baby’s bottle. Simply place the bottle into the warmer, set your desired control and let the machine do the rest. Most bottle warmers are designed to hold just one bottle at a time, but a few two-bottle options are available as well. Some models can also do double duty as a bottle-part sanitizer.
  • Portable Bottle Warmers. If you are out and about with your little one over a mealtime, these warmers can save you the headache of a rejected cold bottle. You have several options when it comes to portable warmers. Some models are electric and run off a battery or car adaptor, while other warmers feature a self-heating element. A few require you to heat the container before you leave home and the warmer will then keep your baby’s bottle at a comfortable temperature for up to a few hours.

Unsafe Ways to Warm a Bottle

While every parent wants to give their hungry baby a bottle as soon as possible, it’s never a good idea to use unsafe methods to save a few minutes.

It is safe to use a microwave or saucepan to heat a bowl of soaking water, but there are several reasons why placing an entire bottle in the microwave or on the stovetop is never recommended.

  • Microwaving results in uneven temperatures and hot spots within the bottle. The outside of a bottle could feel warm to the touch but be dangerously hot on the inside.
  • Microwaving plastic is not recommended. A report from the American Academy of Pediatrics states that BPA could leak out of plastic containers when they are heated in the microwave.
  • Submerging a bottle in boiling water could easily overheat the milk and damage vital nutrients.
  • A sudden temperature change from the refrigerator to boiling water could damage a bottle. This is especially true if your bottle is glass.

Is It Necessary to Warm a Bottle of Breast Milk?

Feeding your baby a bottle of milk straight out of the refrigerator will not harm them. However, babies who are accustomed to a warm bottle or nursing could find a mouthful of cold milk to be a jarring change, and they may reject the feed.

How to Test Milk Temperature

Gently shake a few drops of milk onto your inner wrist to determine how warm your baby’s milk is. The milk should feel just warm, not hot.

Feeding Frozen Milk

How to Thaw Milk

To preserve the greatest amount of nutrients, always thaw breast milk slowly using gentle techniques.

In the Refrigerator – This method is the easiest: simply take your container out of the freezer and place it in the refrigerator.

What you gain in convenience you lose in speed, however. It usually takes a container of milk about 12 hours to fully thaw under refrigeration, so take your milk out of the freezer the night before you plan to use it.

Always thaw all glass bottles under refrigeration.

Under a Stream of Warm Water – This method is certainly faster but will still take a few minutes.

To minimize the temperature shock, turn on a cool stream of water first and gradually increase to a warm, not hot, temperature. Turning the container periodically can help thaw the container evenly and a little faster.

Warming a Bottle of Thawed Milk

Follow the instructions under the “How to Warm a Bottle of Milk” section above.

Transporting Milk

Whether in your daily diaper bag or on a long-haul flight, you may find yourself needing to take your breast milk along for the ride.

Everyday Transporting or Short Trips – Seal the bottle well with a screw-on cap and place the bottle in your bag if all of the following are true:

  • Your milk is freshly pumped.
  • Your baby will be drinking the bottle within a couple of hours.
  • The ambient temperature is less than 79 degrees F.

Use an insulated cooler bag with ice packs in the following situations:

  • Your milk will be exposed to temperatures higher than 79 degrees F.
  • Your baby won’t drink the bottle for a few hours.
  • Your milk has been refrigerated or frozen.

To warm the milk, use a portable bottle warmer, or run the bottle under a stream of warm water if you have access to it.

Transporting for Longer Trips – Fresh milk can be stored safely in an insulated cooler bag with ice packs for up to 24 hours. Use the tips outlined above to warm a bottle.

Longer road trips require colder storage, and packing your milk in dry ice could be a good solution for keeping your milk frozen for up to 48 hours.

Place a layer of dry ice at the bottom of the cooler, then lay your milk containers down next. Finally, place another layer of dry ice over your milk.

Taking proper precautions is crucial when handling dry ice:

  • Use safety goggles and hand protection like heavy work gloves or thick oven mitts.
  • Use hand protection or tongs to pick up items packed in dry ice.
  • Don’t work with or open a container of dry ice in an enclosed space; go outside or choose a large room with good ventilation.
  • Using an airtight cooler could cause the dry ice to explode. A foam cooler usually works best.
  • Put the dry ice in a separate area of the vehicle such as the trunk or truck bed. If your car doesn’t have a separate space, you should not use dry ice.

Flying With Breast Milk – The Transportation Security Administration (TSA) allows breast milk in carry-on bags in reasonable amounts. Individual airlines can have their own rules regarding carry-on baggage, however. Make sure to check with your airline to determine their rules and avoid any surprises at the gate.

If you have a container of milk larger than 3.4 ounces, inform your TSA officer at the beginning of security screening. Containers of this size will go through X-ray.

If your milk is frozen solid, TSA officers will wipe the outside of the container to test for explosive materials. If your milk or any ice packs are liquid or semi-frozen, TSA may ask for a small sample to test for explosive material or other restricted items.

If you want to fly with a larger amount of frozen milk, you can pack it with dry ice in a safe cooler. Follow the safety tips listed above. Notify an airline employee that you are traveling with dry ice as soon as you arrive at the airport.

Shipping Breast Milk – If you are traveling a long distance and plan to feed your baby multiple bottles at your destination, the most convenient option may be shipping your breast milk.

You can use regular ice or dry ice to ship, though dry ice will require specialized shipping containers and should not have an airtight seal. Use the same safety tips listed above for packing a cooler with dry ice.

Always use overnight shipping and have a plan in place to store your milk at your destination.

Handling and storing your breast milk safely can be a true labor of love. You should be proud of yourself for investing the time and effort necessary to learn and follow proper breast milk guidelines.

Whether you are feeding your baby a bottle during an afternoon outing or building a freezer stash to use when you return to work, using stored milk can go a long way toward helping you reach your breastfeeding goals.