Milk is the perfect first food for your baby, as it’s easy to digest and full of all the nutrients he needs.
But it also contains bacteria that can upset his tummy if traces are left on his feeding equipment and given time to multiply.
That’s why we sterilise our babies’ bottles, as this is the best way to kill bacteria.
It makes it impossible for germs to survive and be passed on to your baby. This helps him, as he doesn’t start producing germ-fighting antibodies until he’s six months old, but by the time he reaches his first birthday his body will be able to kill off bacteria all by itself.
What should I sterilise?
If you’re bottle-feeding your baby, you’ll need to sterilise his bottles for as long as he is using them. Formula milk is not sterile and can contain bacteria.
This isn’t a problem unless the used bottle is left at room temperature, when the bacteria can start to multiply within a few hours, which is why it’s vital to sterilise all feeding equipment before your baby’s next feed.
If you’re breastfeeding, sterilise shields if you use them. And if you express your milk, you’ll need to sterilise the bottles and breast pump.
Breastmilk can be kept longer than formula, as it contains enzymes that kill bacteria for 10 hours once it’s expressed, so it’s safe at room temperature for this long. But after 10 hours, new bacteria will appear and again need to be killed off before your baby’s next feed.
Clean everything before you start
Before using your steriliser, wash your baby’s bottle, teats, retaining rings, caps and tongs.
Do this in hot, soapy water, separately to all your other washing up, using a bottle brush.
If you can, turn the teats inside out while washing to make sure any stubborn milk curds come off, as these can survive the sterilising process. Then rinse off the soapy water in cold, running water.
You can put bottles in the dishwasher if they are dishwasher-safe, but not the teats, as they need to be thoroughly washed by hand. As you wash them, check the teats and bottles carefully and throw out any that are badly scratched, split or cracked, as bacteria can survive here. Then put all the equipment, including tongs, into your steriliser.
Should I get a steam steriliser?
Steam sterilisers kill bacteria by blasting them with 100°C water vapour.
Bacteria thrive at 37°C room temperature, but heating to over 100°C kills germs in the same way that it would damage our skin.
Electric steam sterilisers need to be plugged in to the mains and filled with water. Be sure to add the recommended amount of water to the basin, as too little may not sterilise the bottles properly, while too much could cause the basin to overflow.
Load the steriliser by putting bottles in upside down, and don’t add more bottles than recommended. Place teats, rings and caps inside, and space them apart, so the steam can reach all surfaces.
Fit the cover carefully, so there are no gaps for the steam to escape.
Sterilising takes six to 15 minutes, depending on the model, and doesn’t use chemicals or require rinsing. Don’t open the lid until the end of the cooling cycle, as this dries the bottles, while keeping them sterile. And leave the lid on in-between removing the bottles for feeds.
Microwave steam sterilisers also work by heating up water to generate steam.
Again, add the recommended amount of water to the basin and put bottles in upside down, and space out rings and teats to fully sterilise them. The time it takes depends on your microwave, but usually takes eight minutes in an 800 watt microwave, six minutes in a 850-1000 watt, and four minutes in a 1100 watt.
You can sterilise individual bottles in the microwave without a purpose-made steriliser.
If you only occasionally feed with a bottle, this method might work well for you. Before using, clean your microwave and wipe with anti-bacterial wipes. Then fill the bottle half-full with cold tap water and stand upright in the microwave. Next to it, put the teats, rings and caps in a small microwavable bowl, filled with enough cold tap water to cover them. Microwave on full power for one and a half minutes.
Cold soak sterilising
You can also use sterilising fluid or tablets made from sodium chlorate to sterilise bottles in cold water.
This is a chemical that’s been purified, mixed in a salt-water solution. It’s two per cent strength, so is safe to use. Add the solution to a plastic container, either one that’s specifically designed for sterilising, or a simple Tupperware tub is fine.
Fill it with the required amount of cold tap water and add the sterilising tablet or liquid, dunk the bottles and equipment in the water until they are fully submerged and allow them to completely fill with water. Make sure that everything stays under the waterline by using a tray or lid on top of the bottles to weigh them down. The bottles must stay submerged for 30 minutes.
Take a bottle out as and when you need it – once taken out of the solution, a bottle should be used straight away, but it can be safely left in the solution for up to 24 hours. It’s fine to add a used-but-washed bottle to the tub during the day, as long as you wait 30 minutes before taking another one out.
You’ll need to change the solution every 24 hours, when you can dry the bottles with a clean paper towel, or leave them to air dry with the teats facing inside the bottle.
Sterilising while you travel
If you’re away from home, boiling is a handy way of sterilising bottles, but it’s best not to use this method on a regular basis, as it can damage teats.
You’ll need a large pan with a lid or cover, then add enough tap water to completely submerge the bottles and equipment, then keep the water boiling for 10 minutes to kill the bacteria.
If you use plastic bottles, weigh them down with a heavy object, such as a smaller pan lid, so they don’t float to the surface. Ideally, bottles should be used as soon as they are sterilised, but if this isn’t possible, assemble them straightaway to prevent the inside of the bottle and teat from becoming contaminated.
When should I stop sterilising?
There’s no need to sterilise bowls, plates, spoons and beakers once you start weaning, as it’s only the milk bacteria that causes problems.
By age one, he will be able to fight off the bacteria for himself, so you can stop sterilising unless you want to carry on.