There are four main ways to keep a bottle warm. You can put the bottle in a container of warm water, run it under the warm-water tap, prepare the baby’s formula with warm water or use a bottle warmer.
This article will explain the general basics of bottle warming, including what not to do, and then talk you through each of these methods. We’ll also give you some tips for warming your baby’s bottle on the go.
Why warm a baby’s bottle?
The natural temperature of breast milk is about 37C. When your baby is a newborn (0 to 6 months), it’s best to ensure that any formula or expressed milk they receive is also served at this temperature (or close to it). This makes life easier for their fragile stomachs and hence makes life easier for their fragile parents.
Once a baby is past this stage, they will develop their own ideas about the perfect temperature for their milk. Many will still prefer warm milk but will take it at room temperature. Some even start to prefer cool milk, especially in hot weather.
The basics of warming a baby’s bottle
If you think that warming a bottle for a baby is essentially the same as making a warm drink for an adult, then you’re partly right and partly wrong. You’re right in the sense that babies often prefer warm drinks for much the same reasons that adults do, i.e. they’re comforting, especially when it’s cooler.
You’re wrong in the sense that the average cup of tea or coffee is served around 70C to 80C. In other words, an adult’s idea of warm is about twice the temperature of breast milk. If you try serving your baby their milk at this kind of temperature, you’ll not only scald their insides but also destroy a lot of the nutritional value of the milk.
In other words, really, you’re not so much warming the baby’s bottle as just taking the edge off the cold. If your baby’s milk is at the right temperature, you should be able to sprinkle a few drops of it on your wrist or elbow and not really notice it (because it’s so close to your body’s own temperature).
Never warm baby bottles in the microwave
In theory, there is nothing wrong with putting a baby bottle in the microwave to warm it. In practice, it’s just way too easy to overheat the bottle. Although you can leave the milk to cool before you serve it to your baby, you cannot restore the nutritional content lost by overheating it in the first place.
You can keep a bottle of formula warm for up to an hour
If you’re trying to anticipate your baby’s feeding times, you may wind up getting it wrong occasionally and having the bottle ready a bit before they actually want it. As long as you use it up within an hour, you’ll be fine. After that, it has to go down the sink.
If your baby hasn’t started feeding yet, the most practical option is generally to put the milk into a vacuum flask and wait for your baby to let you know they’re hungry. Then just transfer it into a baby bottle and start feeding them.
Keeping a bottle warm while feeding
If your baby is a leisurely eater and you are concerned about their milk getting cold, you can keep a vacuum flask beside you and pop the bottle into that while your baby is on a break. For this to work, you need to keep the stopper on the flask between uses. If, however, your baby is older than 6 months, then you can probably just let the milk cool down to room temperature. Their stomach should be able to handle it and, unless they’re really fussy, if they’re hungry, they’ll eat it.
Never reuse baby milk once it’s been warmed
While it’s important to eliminate food waste, it’s even more important to avoid giving your baby food poisoning. This means that once baby milk has been warmed, you have an hour to use it. If your baby doesn’t finish it, too bad, it goes down the sink.
Warming a bottle in a container of water
Heat enough water to fill a container which will hold your bottle at least up to the neck. You can do this in a pot on the stove, put a bowl in the microwave or boil a kettle and use that to fill a bowl. Once you’ve heated the water, you may need to let it cool before you put in your bottle. You want it about the sort of temperature you’d use if you were washing your hands thoroughly. In other words, you want it to be warm, bordering on hot, not clearly hot and certainly not boiling.
With your water ready, you just pop in your bottle and wait. How long it will take will depend on the type of bottle you’re using 10-15 minutes is a reasonable guideline. You might want to try practising when your baby’s not hungry. You don’t have to waste formula, just try heating plain water.
Warming a bottle with the hot water tap
You can warm baby bottles just by running them under the hot tap, but there’s not a lot to be said for this option. First of all, it uses a lot of water and secondly it requires you to stand there for the length of time it takes to warm the bottle, which is usually 10-15 minutes. That’s 10-15 minutes you could have spent doing something else, like changing your baby’s nappy. It takes less time to warm up milk bags, usually about 5 minutes or thereabouts, but even so, that’s 5 minutes you could have used for something else.
Make your formula with warmed water
Heat water to a point where you can put a finger in it and be comfortable, then use it to make up your formula. In theory, you can do this just with the tap. In practice, there are likely to be two potential issues.
First of all, many areas of the UK have limescale. If you have a water softener, this may solve that problem, but this is not guaranteed. Secondly, even if you have soft water, you may find that the water temperature changes. This could result in you accidentally overheating your milk.
Another option would be to heat some water, put it in a thermos and leave it. Then, when you’re ready to make up your formula, add cold water and then top it up with water from the thermos to make warm milk (or at least to get the milk up to room temperature). Always put in the cold water before the hot to reduce the risk of overheating the milk.
It may take a bit of practice to get the correct ratio, again you can do this with plain water while your baby’s otherwise occupied.
Use a bottle warmer
A bottle warmer may seem like an extravagance, given that, technically, you don’t need to heat the milk at all, not even for newborns. On the other hand, babies up to 6 months generally have a strong preference for heated milk and keeping them (and their fragile stomachs) happy generally makes life more comfortable for everyone.
If you are going to buy a bottle warmer, make sure it will fit all the bottles you intend to use, Many bottle warmers will fit a variety of baby bottles, but if you buy one from a baby bottle manufacturer, then it may be designed to work just with their own brand of baby bottles.
Improvised bottle warmers
If you feel you really can’t justify buying a proper bottle warmer, then you might want to think about buying a very small slow cooker and just leaving it on continually. Then when your bottle warming time is past, you can just use it as a slow cooker (or pass it on to someone else).
Always test the water temperature before you feed your baby
Whatever bottle warming method you use, always double-check the temperature of the milk before you feed your baby. Give your bottle a good swirl (don’t shake it) to make sure that the milk is properly mixed and that the temperature is even throughout the bottle. Then push out a few drops onto your hand, wrist or elbow. It should be about the same temperature as your body.
Warming a bottle at night
During the day, there’s probably a decent fighting chance that you will be able to anticipate when your baby is likely to want fed. At the very least, you’ll have a chance to pick up on the early-warning signs that their stomach is starting to grumble. This gives you the opportunity to get the nipple into their mouth before they turn into a hanger-fuelled monster.
At night, however, it’s more likely that you’ll be woken up by your baby letting you know that they want fed NOW. It can therefore be a smart move to invest in some reusable breast milk pouches even if you’re only using formula. The reason this is a smart move is because breast milk bags have a very large surface area, so they warm very quickly. Then you just pour the milk into a regular baby bottle and start feeding.
Pro tip, if it’s a long trip to your kitchen, save yourself some time by storing what you’ll need for your night-time feed(s) in your baby’s nursery. You can put your ready-made feed(s) into a cool bag with freezer packs and keep hot water in a thermos. You’ll also need a bowl to hold the water when you want to warm the feed and, of course, a bottle. You might also want a funnel to make it easier to transfer the milk from the bag to the bottle.
Warm milk on the go
You can buy bottle warmers for use on the move. If you’re interested in this option, then remember to think about what you will do for power. If you only have a standard 12VDC car adapter, then you’ll only be able to use it in a car. If, however, you have a USB adapter, then you can use a power bank. If you can use batteries as well, then you have even more options for providing your baby with a warm meal.
Alternatively, you can go down the old-fashioned route of just portioning out your formula before you leave. When your baby is ready to eat, add cold (lukewarm) water to mix and then warm it up with water from a thermos.
A word on baby bottles
Baby bottles come in four main materials. These are silicone, plastic, glass and stainless steel.
If you opt for glass, then you will need to be very careful when you warm your bottle. First of all, glass is heat-sensitive and secondly, it can be very slippery. Using a silicone sleeve can help with both of these issues, but you will still need to be careful.
Silicon, plastic and stainless steel are all fairly easy to warm. Be aware, however, that while plastic will generally stay in one piece when it’s dropped, it can’t take the sort of abuse silicon and stainless steel can handle. It may not shatter the way glass will but it can crack or spring a leak.
Some modern baby bottles come with “venting systems”. These are great if you want to stop your baby gulping down air. The only downside is that they generally involve inserting extra parts into a bottle and these generally have to be removed before you warm it.
It’s fine to stock up on baby bottles before your little one arrives, but you might want to hold off stocking up on nipples. Instead, pick up one of each of the three main types (narrow and long, wide and short, and flat on one side) and see which one your baby prefers.