How to make up your baby’s formula milk feed

boiling kettle with dense steam

Contrary to a once long-held belief, powdered infant formula milk is not sterile. Therefore, even though tins of powdered formula milk have been sealed from the time that they were manufactured, they may still contain bacteria that can be harmful to your baby’s health. While the presence of harmful bacteria in powdered infant formula is rare, where babies have become ill, this illness can be life-threatening and there have been a number of cases where babies have tragically died. Because your baby is born with an immature immune system they are a lot more susceptible to infections and cannot fight them off as easily as we can. Concerns about the bacteria that may be present in powdered infant formula milk has prompted the Department of Health to issue stringent guidance on how to safely store and make up powdered infant formula milk feeds. See also our article on ‘Formula milk (bottle) feeding your baby’.


New safety guidance

The main change in the guidance is that each infant milk feed should be made up as your baby requires it. While it can be very tempting to make up several feeds at once to last your baby throughout the day and night, this is actually a hazardous practice. The new guidance aims to reduce the incidence of harmful bacterial infections making your baby ill. The Department of Health therefore recommends that you make up each feed as your baby requires it using boiled water at a temperature of 70oC or higher. This is because water at this temperature kills any harmful bacteria that might be present in the powdered infant formula milk.


Best practice in making up your baby’s formula milk feed

a). Hand hygiene is very important, so before you start to make up your baby’s formula feed, ensure that you have washed your hands thoroughly with soap and water. You should also make sure that the kitchen work surface is clean, so wipe it down with hot soapy water, antibacterial wipes or surface cleaner

b). Ensure your baby’s feeding equipment has been sterilised before you begin to prepare the formula feed. See also our article on ‘Sterilising your baby’s feeding equipment’

c). Tap water is perfectly safe to use for making up your baby’s formula feed providing it has been freshly boiled and then cooled slightly to a temperature of 70oC or higher. You should never use water that has been previously boiled or artificially softened; this is because the processes involved affect the mineral balance of the water which can make it unsuitable for babies

d). The water in your baby’s feeding bottle needs to be hot when you add in the scoops of powdered formula milk. This is because the heat kills off any harmful bacteria that might be present. For this reason, you should never boil up the water in advance and store it in sterilised bottles in the fridge

e). It is recommended that bottled water is not used to make up your baby’s formula milk feeds. This is because bottled water is not sterile and could contain too much sodium (salt) or sulphur. If circumstances mean you have no option other than to use bottled water, it will need to be boiled before it can be used to make up your baby’s feed. NB. Bottled ‘mineral’ water may contain too much sodium (salt) or high levels of sulphate, so it is important that you check the bottle label carefully. Sodium (Na) levels should be less than 200 milligrams (mg) per litre of water and sulphate (SO4) should not exceed 250 milligrams (mg) per litre.


How to make up a ‘powdered formula milk feed’

This next section offers some easy-to-follow instructions on how to make up your baby’s formula milk feed.

  1. Using fresh cold tap water, fill your kettle up with 1 litre (1000 ml) of water
  2. Bring the water to the boil; then leave it in the kettle to cool for no longer than 30 minutes – this ensures the water remains at a temperature of 70oC
  3. Make sure you have washed your hands thoroughly and have cleaned the kitchen work surface where you will be making up the formula milk feed
  4. Ensure your baby’s feeding equipment is sterilised – equipment that has been steam sterilised or boiled in water can be used straightaway. However, if you are using a cold water sterilising system, you will need to shake off the excess sterilising solution from inside the feeding bottle and teat. You may prefer to rinse away any excess sterilising solution; if this is the case, rinse the feeding equipment with cooled boiled water from the kettle
  5. You should always follow the manufacturers’ guidance on how to use their powdered infant formula milk. There are a wide range of infant formula milks available on the market, so it is important that you follow the individual manufacturer’s instructions stringently. You should also use the measuring scoop that is provided with the tin of formula
  6. Stand your baby’s bottle upright on the cleaned work surface; however, you should not place the bottle teat and cover/lid on the work surface. Instead, keep the sterilised teat and cover/lid on the upturned lid of the steriliser
  7. Always pour the correct measure of hot water into the bottle first and ensure the water is at the correct level. You may feel that it doesn’t really matter which is added first – the water or the powdered milk? However, it is extremely important that the hot water is poured into the bottle first, as this ensures your baby’s formula milk feed is made up to the correct concentration. NB. Adding too much powdered milk can make the feed too concentrated and your baby could become dehydrated, constipated and ill. If feeds are made up with insufficient formula milk, your baby will not receive the nutrition that they require for healthy growth and development, and they can lose weight. You will need to follow the manufacturer’s instructions on the tin of formula milk – this information includes a table that gives the number of scoops of milk needed per millilitres (ml) of water
  8. Loosely fill the measuring scoop with powdered milk; do not be tempted to pack the powdered milk into the scoop. Level off the top of the scoop using the leveller provided with the tin of formula, or use the flat edge (not the blade) of a clean, dry knife. NB. Always use the measuring scoop provided with the tin of infant formula milk. Different brands of formula milks have different measuring scoops and these should never be used interchangeably
  9. Without touching the actual teat, hold the edge of the teat and place it onto the top of the bottle, then screw the teat’s retaining ring onto the top of the bottle. Put the cover/lid on the teat so that it is covered/protected
  10. Shake the bottle vigorously until all the powdered formula milk has dissolved in the hot water – this shouldn’t take too long!
  11. You will obviously need to cool down the formula milk before you feed it to your baby. There are simple ways you can do this – you can stand the feeding bottle in cold water or place it under cold running tap water. You will however, need to keep moving the bottle to ensure its contents are cooled evenly
  12. Test the temperature of the milk to ensure it’s not too hot for your baby. You can do this by allowing a few drops of milk to fall onto the inside of your forearm – just above the wrist. We advise this area because your hands and wrists tend to get used to being submerged in hot water, whereas the area of skin a little higher up the arm remains more sensitive to temperature changes. You are aiming for the formula milk to be at body temperature so it should feel warm or slightly cool, but not hot
  13. Once your baby has finished feeding, any formula milk left over should always be discarded
  14. Do not add any other foods (eg cereal, sugar, syrup, coco powder) to your baby’s formula milk
  15. Avoid using microwave ovens for warming your baby’s milk. These do not warm the milk through evenly and there can be ‘hot’ spots which can scald/burn your baby’s mouth and throat.
Baby Friendly Initiative (2010). A guide to infant formula for parents who are bottle feeding. London: UNICEF UK Baby Friendly Initiative. 8 pages.

Baby Friendly Initiative (2010). The health professional’s guide to: “A guide to infant formula for parents who are bottle feeding”. London: UNICEF UK Baby Friendly Initiative. 21 pages.

Department of Health (2010). A step-by-step guide to preparing a powdered formula feed. London: Department of Health. 2 pages.

Department of Health (2013). Preparation of infant formula. London: DH  23 January 2013.

Herbold NH, Scott E (2008). A pilot study describing infant formula preparation and feeding practices. International Journal of Environmental Health Research 18(6):451-459.

Holmes D (2010). Infant feeding. In: Lumsden H and Holmes D eds. Care of the newborn by ten teachers. London: Hodder Arnold. 65-77.

Jordan J (2005). I’m going to have a baby!Wigan: Teenage Pregnancy Team. 59 pages.

Lakshman R, Ogilvie D, Ong KK (2009). Mothers’ experiences of bottle-feeding: a systematic review of qualitative and quantitative studies. Archives of Disease in Childhood 94(8):596-601.

Needs of bottle-feeding mums neglected (2009). Practising Midwife 12(8):12.

Osborn K, Lyons M (2010). Is bottled water really unsafe for making up infant formula? Community Practitioner 83(3):31-34.

Scowen P (2009). Bottle-feeding mothers and babies matter too. Journal of Family Health Care 19(4):112.

Start4Life (2010). Guide to bottle feeding: how to prepare infant formula and sterilise feeding equipment to minimise the risks to your baby. London: Department of Health. 22 pages.

Wall A (2006). Constipation in babies under 6 months old. Family Health Care Bulletin 16(6), suppl 1:2 pages.

Waterston AJR (2009). Your Babycare Bible. London: Carroll and Brown. 392 pages.