I get it, I do. Making up powdered infant formula as dictated by the box is a pain. But there's a reason they give the instructions. There's a reason why the World Health Organisation (WHO) and the NHS recommend the water used to make the formula is over 70°C.

Powdered formula production isn't a sterile process so it contains bacteria that needs to be destroyed before your baby drinks the milk it makes. The water temperature needed to destroy this bacteria needs to be 70°C or above. Bacteria found in formula powder can include Salmonella and Cronobacter. Studies have found that gastro-intestinal infections in young babies occur most often in formula fed babies than breastfed babies with at least 3000 hospitalisations being attributed to the use of formula in the UK every year. Preparing the formula correctly is an important step in reducing the number of such hospitalisations!

So, what's wrong with the prep machines then? They kill the bacteria right? Well...

Research has actually found that the quantity of water in the 'hot shot' a prep-machine dispenses is not sufficient to remain at the the necessary temperature for long enough to kill any of the dangerous bacteria! In fact, only just under 15% of 74 prep-machines that were tested produced water at the necessary temperature. In contrast, when using a kettle, 78% of the 69 kettle users, reached the right temperature to safely make up the powdered formula. The average temperature from a prep machine was 65.78°C.

Meanwhile, creating home-made alternatives to these machines i.e. with some freshly boiled water and some cool boiled water is equally not a proven way of safely destroying all the necessary dangers.

Having worked with a lot of families over the years, I am very conscious that these machines can be a real life-saver in terms of feeding a hungry baby in a busy household as well as, of course, making a bottle quickly in the middle of the night. It is, however, important to understand the reasons behind why they may not be the best choice for your smallest offspring, who's digestive and immune systems are at their most immature and vulnerable.

Personally, when I make up formula, I boil a kettle of 1 litre of fresh water, leave it for a short while to cool (the formula companies normally say a max. of 30 minutes but I do far less...more like 10), pour in the necessary amount, add the formula and combine, and then cool the bottle. I do this by first running it under a cold tap for a little while and then placing in a bowl of cold water. I normally empty and re-fill the bowl after a few minutes and within 10, testing the milk temperature on the inside of my wrist, it is just the right temperature for a happy baby.

I think often the worry is that this process takes too long and when a baby is hungry, they want their milk now. However:

1. If baby becomes upset waiting, you can still be responsive; holding and soothing baby, using a dummy if necessary, until he is calm and until the milk is ready

2. There are often early signs that baby may want a feed - either because it's approaching a while since their last one or because they're showing early hunger cues. At this point, you can make a bottle - even if baby doesn't actively feed for another 30 minutes, the milk is still good to go and you've not had to rush. According to the NHS guidance, a bottle of formula can be at room temperature for 2 hours and in the fridge for 24 hours - although it is always safest and most recommended to be prepared fresh. 

Remember, your little formula-feeding baby only needs it for the first year. After that first year of kettle-boiling, you can (normally) choose to never touch a box of powdered formula again. 

If your little one is showing any signs of discomfort after feeding, tummy pains or you're concerned about aspects of their nappy output, try skipping the prep machine and taking the old-fashioned route to see if that helps...Of course, if baby seems unwell, seek medical attention.

Click here  for the research paper on which this post is based.