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Warming infant formula

If feeding your baby infant formula, it is important you follow good food safety practices. You should:

• store infant formula powder in a sealed container in a cool dry place

• clean and sterilise feeding and preparation equipment until your baby is three months old

• prepare formula following the manufacturer’s instructions.

It’s best to mix the powder with cooled, boiled water just before you give it to your baby. If this isn’t possible, the made up formula can be stored at room temperature for up to two hours or in a refrigerator for four hours.

Infant formula powder is not a sterile product. Most healthy full term babies will not be affected, but once in a while formula powder may contain bugs that can cause serious illness.

If you choose to warm formula for your baby, it’s important you never re-heat warmed or partly-used feeds. Always check the temperature of the formula by shaking some of the formula on the inside of your wrist (without touching the teat). The formula is safe for the baby when it feels just warm.

Options for warming

• Place the bottle of prepared formula in a container of hot water. Before feeding your baby shake the bottle thoroughly to ensure the formula is an even temperature. Always test the temperature so the formula is safe for your baby.

• Use a commercially available device designed specifically to warm baby bottles. Most of these devices are electric and aim to warm the bottle to an appropriate temperature for your baby within a few minutes. Electronic baby bottle warmers are safe to use as long as the manufacturers instructions are followed carefully. Ideally, choose a warmer that sounds an alarm when the appropriate temperature is reached and then automatically switches off. Always shake the bottle once warmed and check the temperature of the milk before giving it to your baby.

• Some baby bottle warmers use other ways to heat the milk. A model designed for in the car uses the car battery as an energy source to heat the milk. Other products have a re-usable warmer pouch which can be activated by bending a metal disc attached. Both of these products are safe to use as long as the formula is made up by mixing the water and powder together just before warming. Remove the formula from the bottle warmer and finish feeding your baby within two hours. Throw out any unused formula.

• Microwaves are not recommended for warming bottles of infant formula because they can overheat the milk or heat it unevenly. This can cause nasty burns to the baby’s mouth and throat. If you need to use a microwave follow these steps:

- half way through the heating process, stop the microwave, remove the formula and shake it thoroughly. Continue the heating process

- after heating let the formula stand for two to three minutes

- shake the bottle again and check the temperature of the milk before giving it to your baby.

Ideally, once the formula is made up, use it straight away and throw out any remaining formula.

For more information on preparing and using infant formula safely please ask your Lead Maternity Carer or your Plunket Nurse.

Related links

• Safe feeding for infants

Updated 13 October 2009