baby bottle

How do you warm up a bottle without a warmer?

It’s nearly impossible to feed Baby straight from the boob at every single meal. Your job, social obligations, sleep schedules, and plenty of other things will inevitably get in the way. The solution? If you don’t want to stop breastfeeding, you can pump and store your breast milk.

Pumped milk will stay good for 3 to 5 days in the fridge and up to 6 months in the freezer, although it may lose some nutritional and antioxidant properties. (Baby will still get plenty of benefits, though!)

Before serving stored milk to your little one, you’ll probably warm it somewhere between room temperature and body temperature. Aim for around 99 degrees Fahrenheit as a guideline. Here’s how to warm up breast milk safely and effectively. 

Baby’s hungry, and it’s T-minus a few minutes before it turns to hangry – but do you feed them a bottle straight from the fridge, or do you take the time to warm it up? Some little ones are perfectly fine with a cold bottle, while others have to have it warmed to perfection.

If your baby is among the warm party – or you’ve found that a warm bottle before bedtime or naptime helps them fall asleep faster and sleep longer – fret not. We have tips and tricks to warm a baby bottle in no time.

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The Basics of Bottle-Heating

First of all, let’s make one thing clear: It’s not medically necessary to heat a baby’s bottle; it is a matter of preference. While young babies, especially, may have a strong preference for warm milk, older babies may be more open to tolerating lukewarm or cold milk.

When a baby nurses, the milk that is released is body temperature, around 98.6 degrees. For us adults who like our coffee around 160 degrees, that seems downright icy, which is why “Heating” a bottle is a misnomer.

Bottles that are microwaved also continue to “cook” after they’re removed, making the temperature increase further and putting your baby at risk for burns.

Heating bottles on the stove-top in boiling water can also cause milk to heat unevenly, warm too quickly, or overheat all at once. You can heat water on the stove and then use it to warm a bottle, but make sure to remove it from the stove before putting the bottle in to warm. Bottle warmers or a mug of warm tap water are a safer bet.

If your baby prefers their milk warmed, check out our advice below to make sure you’re finding that perfect temperature quickly and safely.

baby bottle

Choose a Glass or BPA-free Bottle

When you’re heating your baby’s bottle, it’s important to be mindful of the possibility of chemical leaching. Glass bottles are a great choice to give you peace of mind. Still, some parents are dissuaded by their weight and the possibility of breakage.

The good news is that these days all baby bottles sold in the U.S. are manufactured without bisphenol A (BPA) if you’d prefer to use plastic. BPA (used to make rigid plastics, keep plastics from growing bacteria and prevent rust) is an estrogen-like chemical that can potentially cause health problems.

If you are using old or secondhand plastic bottles, you may want to check whether or not they contain BPA. You may also need to check this if your bottles were purchased outside of the U.S. Consult the manufacturer to ask if you’re not sure.

Why Should You Warm Breast Milk?

There’s no harm in giving your baby cold milk. But breast milk is warm when babies nurse, so they’ll prefer the familiarity of the temperature. Warming the milk also helps mix everything (fat tends to separate when milk is cooled down in the fridge or freezer). 

Be careful not to go overboard, though: Too much heat can destroy the milk’s enzymes and immunizing properties. Plus, warming milk above 104 °F might scald your baby.  

Bottle Warming Options

While the ideal milk temperature is at or just below body temperature – 98.6 degrees Fahrenheit – that’s more of a guideline. Before you bust out the thermometer, consider the wrist method to test the temperature: drop a couple of dribbles from the bottle onto the inside of your wrist. If it feels cold, warm it up a little more; if it feels hot, let it cool. Bonus tip: after warming the bottle, swirl the contents around to ensure consistent temperature throughout.

If you prefer to use the bottles you have but aren’t sure about their BPA content, don’t worry, you can still use them! Just heat your milk or formula in a glass container and then transfer it to your existing bottles to avoid the leaching issue.

Heat Evenly

While most of these methods heat your baby’s bottles evenly, it’s always better to be safe than sorry. Gently swirl (don’t shake) the milk to mix it up and make sure there are no hot spots and that the temperature is consistent throughout the bottle.

Test the Temperature

No matter which method you use, remember — safety first! Always test the milk before giving the bottle to your baby to avoid burning their mouth. Dab a few drops of milk onto your inner wrist; you should feel almost nothing if it’s the appropriate temperature.

Most babies prefer milk that’s as close to body temperature as possible. If you feel no warm sensation on your wrist, the temperature is perfect. If it’s slightly cool, it may still be acceptable, but if you feel any heat at all, the bottle is too hot. Wait until it cools down to offer it to your little one.

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Ways to Safely Warm Your Baby’s Bottle

Set the Bottle in Warm Water

One of the most tried-and-true bottle-warming methods is the counter-top method — and it requires no special equipment! Heat some water on the stove, in the microwave, or run the hot water tap. The water should be warm (not hot) but not boiling.

Remove the water from the heat source and place the bottle into it, allowing it just to sit and be gently warmed by the water. Swirl the bottle occasionally to make sure all the milk gets heated through, but avoid shaking vigorously as this can introduce air bubbles.

This method is easy and costs nothing, but it can take several minutes to warm your baby’s bottle to the desired temperature.

Warm Milk Bags Under Tap Water

If you’re feeding your baby expressed breast milk, the milk bag is your new best friend!

Because the plastic is thin, and the breast milk is spread across the bag in a thin layer, you can bring it up to the right temperature quickly and efficiently by just running the bag under warm tap water.

When it feels like it’s heated through, transfer the milk to your bottle.

Prepare Formula Bottles with Warm Tap Water

If you’re mixing a bottle of formula and have a sink on hand, there’s no need to go through the extra step of heating your bottle. Run warm water directly into the bottle when you’re mixing your formula.

If you’re concerned about the purity of your local tap water, boil it for one minute and then allow it to cool to the appropriate temperature (98.6 degrees) before making your baby’s bottle.

Use a Bottle Warmer

There are several different options on the market, so make sure you choose one that fits the size and shape of the bottles you’re using. These take the guesswork out of warming bottles — a simple touch of a button warms your bottle to the perfect temperature, hands-free.

There are even some that are made for the car in case you’re away from home. And if you’re formula-feeding, you can choose one that dispenses, mixes, and heats the water all in one simple step. It’s like a Keurig for your baby!

Here are a few other options that might work better

Leave your freshly pumped milk out at room temperature after you pump it.

Whether this will work for you depends on how long your baby usually sleeps, and how warm “room temperature” is in your house at night. Kellymom defines it as between 61 and 79 degrees Fahrenheit (16-26 degrees Celsius) and states that breast milk will be fine at these temperatures for 4-8 hours (though between 3-4 hours are ideal).

So, assuming a) your house is cooler than 80 degrees, and b) it will be less than 8 hours between when you pump the milk and when your baby will drink it, it’s fine to feed it to your baby when he wakes up.

This is the method that I used with my baby – I took a bottle up to my room after my 10 pm pumping session, and my baby usually woke up around 4 am to eat it. On the rare occasions that we’d both sleep until 6 am or later, I would dump the milk because it had been out longer than eight hours.

That’s one disadvantage of this method – you may have to dump your milk if you and your baby don’t end up waking up for a feeding.

(Another option – a reader mentioned that she brings a small cooler to bed with her, with one bottle of fresh milk and the other refrigerated. She gives the baby the first bottle of fresh milk for the first feed, and at that time takes the other bottle out of the cooler, allowing it to warm up before the baby’s second feeding of the night.)

Use a bottle warmer to warm the milk, with everything ready to go.

If using freshly pumped milk isn’t an option (if you’re using a frozen stash or are supplementing with formula), a better option than running the bottle under hot water might be prepping the bottle ahead of time and keeping it in a cooler in your room along with a bottle warmer for night feedings that are all set up and ready to go.

Then when baby wakes up, you have to take the bottle out, put it in the warmer, press start and bounce your baby for a minute while it warms.

If you don’t have a bottle warmer, you can microwave a bowl of hot water for 60-90 seconds and put the bottle in that for a minute or so to warm. This is less easy to do in the middle of the night – and it’s not as fast, you have to go to the kitchen, and it’s harder to juggle a baby when doing this versus pushing a button – but it’s much faster than running a bottle under warm water in the sink.

Note that you should never heat baby bottles in the microwave due to “hot spots” that could burn your baby’s mouth.

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See if your baby will take cold bottles (and skip warming altogether)

Do you need to warm your baby’s bottle? No. There’s no medical reason to warm breast milk, and it’s just that some babies prefer it and get used it to warm.

So you don’t need to warm your baby’s bottle if he’ll take it cold, and it will make your life way easier if you don’t have to worry about warming every bottle you give your baby and can start feeding your milk right from the fridge.

It’s possible you’ve already tried this, but if not, give it a shot!

I would start by offering a cold bottle during the day (the middle of the night is not the time for experiments) and seeing if your baby will take it.

If your baby rejects it, you can try warming it a bit (maybe not as much as you normally would), and see if that is acceptable. If it is, you can see if gradually bringing the temperature down – until it’s not necessary to heat it at all – will work.

This won’t work for every baby – some will refuse cold milk, no matter what you do – and you may have to try this a few times under different circumstances. Try it with you offering it, with someone else offering it, when your baby is really hungry, when he’s not as hungry, etc.

It’s only safe to warm expressed breastmilk or ready-made formula in a bottle, and there are a couple of easy ways to do it:

  • Fill a jug or bowl with warm water. Place the bottle in the warm water for no more than 15 minutes, as any longer could cause bacteria to develop. The water should be hot enough to heat the bottle, but cool enough so that you can place your hand in it. Seal the bottle with a cap over the teat while it’s in the water. Once the bottle is warmed through, shake it to make sure the temperature is even.
  • Use an electric bottle warmer. It will take around four minutes to six minutes to heat a bottle to the perfect temperature for your baby. You could also get a journey warmer to use when you’re out and about.

It’s best not to heat a bottle of formula you’ve made from powder earlier in the day. Mix a fresh bottle of formula for each feed. Even if you store formula milk in the fridge, bacteria can develop slowly.

There may be times when you have to make a feed and keep it in the fridge to heat up when needed. This may be the case if you have twins, or if you’re out for the day, or if your baby goes to childcare. Read more about storing formula in the fridge safely.

When you’ve warmed your baby’s bottle, test the temperature of the milk by squirting a little on to your inner wrist. This is a reliable guide as the skin on your inner wrist is thinner and more sensitive than the skin on your hands. The milk droplets on your skin should feel warm, not hot.

Don’t warm your baby’s milk in a microwave, because uneven pockets of scalding milk can form. The milk will also continue to heat up for some time after you’ve taken it out of the microwave. Some babies have had burns to the mouth and throat after drinking microwaved milk. The intense heat produced in a microwave may also destroy some of the nutrients in your baby’s milk.

If you haven’t timed to warm up a bottle, you may find your baby is happy with milk at room temperature.

While a baby can take a cold bottle, the reality is most of them prefer not to. Using an electric bottle-warmer or setting a bottle in warm water on the counter are two of the best ways to heat milk — but you still need to be mindful of safety and ensure the temperature is even.

I think all mothers can relate to frantically wanting to feed their screaming baby as quickly as possible, but we need to make sure we’re doing it the right way, every time.

What’s your favourite bottle-warming method? Comment below or share with another mama who’s trying to keep her sanity while bouncing a hungry babe on her hip!

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