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Safe feeding for infants

Breast milk is best for babies and all mothers should be encouraged to breastfeed their babies. Breast milk contains all the nutrition newborn babies need and breastfeeding benefits both the mother and the baby. However, parents who have made the decision to feed their baby infant formula, either exclusively or in combination with breast milk, need guidance on the safe preparation and storage of infant formula. Both expressed breast milk and infant formula need careful preparation and storage to ensure they are safe.

Infants can be susceptible to infections as their immune systems are still developing. Although infant formula is produced in hygienic and carefully controlled conditions, it is not sterile and can contain low levels of bacteria. Preparing milk correctly can minimise the growth of harmful bacteria.

By following these guidelines, you can help ensure you handle expressed breast milk and infant formula safely.

Please note these guidelines are for feeding expressed breast milk and infant formula to healthy full-term babies only. Please consult with your health professional for advice on feeding infant formula to your baby if your baby is premature, of low birth weight or very sick.

Cleaning and sterilising bottles and feeding equipment

To reduce the risk of contamination, all bottles and feeding equipment must be sterilised until your baby is three months old. Equipment can be sterilised with boiling water, with sterilising solution, or with a steam-sterilising unit. Please note that a dishwasher does not sterilise bottles or feeding equipment. After three months of age it is sufficient to wash bottles and feeding equipment with hot soapy water and then rinse.

To clean and sterilise your baby’s feeding equipment

1. Always thoroughly wash and dry your hands with soap and water before cleaning and sterilising bottles and feeding equipment.

2. Make sure the area used to clean and sterilise your baby’s bottle and feeding equipment is clean.

3. Wash bottles and feeding equipment thoroughly in hot soapy water. If using feeding bottles, use clean bottle and teat brushes to scrub the inside and outside of the bottles and teats to ensure all remaining feed is removed.

4. Rinse the bottles and feeding equipment well in hot water and air dry it, or wash it in a dishwasher.

5. To sterilise by boiling:

• place the bottles, feeding equipment and preparation utensils in a pot

• if you use glass bottles, a clean cloth in the bottom of the pot may stop bottles from chipping

• fill the pot with water, high enough to cover everything

• bring the water to boil and boil for five minutes, turn off element, and keep pot covered until feeding equipment is needed

• use clean tongs to lift the bottles out and place them on a clean dry surface

• if equipment is not used immediately cover and store in a clean place. Store bottles with the teat upside-down in the bottle, or cover the teat with the sterile cap.

For other methods of sterilisation follow the manufacturer’s instructions carefully, these methods include:

• chemical sterilisation using sterilising solution in a plastic container

• microwave sterilisation using a special microwave steam-sterilising unit. This is not suitable for glass bottles

• steam sterilisation.

Guidelines for handling and storing expressed breast milk safely

Always thoroughly wash and dry your hands with soap and water before expressing breast milk.

You can store breast milk safely in a clean plastic or glass container with a lid. Until your baby is three months old, the container also needs to be sterilised. You can also freeze it.

Each time you express breast milk, store it in a separate container. Do not add it to other breast milk you expressed earlier, especially frozen breast milk.

Adding new expressed breast milk to frozen breast milk may cause some of the frozen milk to thaw and then refreeze. This increases the risk of bacterial growth in the milk, which might harm your baby.

Storage of breast milk	Storage time	Comments
Stored at room temperature (less than 26oC)	4 hours	Cover containers and keep them as cool as possible (e.g. surround the closed container with a cool towel to help to keep the milk cooler)
Refrigerated breast milk (less than 4oC)	48 hours	Store milk in the back of the main body of the refrigerator
Frozen breast milk stored in the:		Store milk towards the back of the freezer, where the temperature is most constant
- freezer box within a refrigerator	2 weeks
- separate door fridge/ freezer	3 to 6 months
- separate deep freeze	6 to 12 months

Source: Food and Nutrition Guidelines for Healthy Infants and Toddlers (Aged 0-2) [Ministry of Health]

How to thaw and warm expressed breast milk safely

Do not thaw or warm expressed breast milk in the microwave as this destroys the living cells in the milk.

To thaw expressed breast milk

Frozen breast milk can be thawed in the refrigerator or alternatively, put the container into a bowl of warm water.

Clean the cup or bottle before you put the thawed breast milk into it. Until your baby is three months old, the cup or bottle also needs to be sterilised. Refer to the Cleaning and sterilising your baby’s feeding equipment section above.

To warm expressed breast milk

1. Fill a bowl with hot water.

2. Put the cup or bottle containing the expressed breast milk into the bowl filled with hot water.

3. Before feeding, thoroughly shake the bottle. Then test the temperature of the expressed breast milk by shaking a few drops onto the inside of your wrist. If the milk is comfortably warm to the touch, it will be about the same temperature as fresh breast milk.

4. Expressed breast milk should not be warmed in the microwave.

5. Use warmed expressed breast milk within two hours.

6. Throw out any expressed breast milk left in the bottle after a feed, and wash and re-sterilise the bottle. Never reheat expressed breast milk more than once.

Storing expressed breast milk while travelling

While travelling, it is important to keep expressed breast milk safe. You can keep expressed breast milk cold for up to four hours in a thermos flask. Do not use a thermos flask that is also used for any other food or drink – have one that is just for expressed breast milk. Also, do not use a thermos flask to carry warm milk as this can increase the risk of bacterial growth in the milk.

Before use, wash the thermos flask in hot soapy water and rinse with boiled water. Until your baby is three months old, you also need to sterilise the thermos flask before use. Refer to the Cleaning and sterilising your baby’s feeding equipment section above.

How to store and prepare powdered formula safely

Keep powdered formula covered and in a clean dry place. Check the use-by-date and use it within four weeks of opening.

As outlined above, clean all feeding equipment before preparing formula. Until your baby is three months old, you also need to sterilise all feeding equipment. Refer to the Cleaning and sterilising your baby’s feeding equipment section above.

To prepare powdered formula safely

1. Always thoroughly wash and dry your hands with soap and water before preparing bottle feeds.

2. Make sure the area used to make up your baby’s feed is clean.

3. Make up formula with cold, previously boiled water. For at least the first three months of your baby’s life, all water (including bought water), used to make up formula should be boiled and chilled on the same day it is to be used. To do this, boil water for three minutes on the stove top or if using an automatic kettle wait until it switches off. Keep boiled water covered while it cools and place in the fridge in sterilised bottles or a sterilised jug until it is needed. Keep this water for no longer than 24 hours. Water from tanks or bore holes should be boiled and cooled for babies and toddlers until they are about 18 months old.

4. Pour an appropriate amount of cooled boiled water into the cleaned and sterilised bottle before adding the powdered formula. Use the scoop and preparation instructions provided with the product. Never add more powder or less water than recommended and never add anything else into the formula feed.

5. If possible, infant formula should be made up just before a feed. Throw out any formula that has been out of the refrigerator for more than two hours.

6. Prepared formula can be stored for later use in the back of the refrigerator at less than 4°C. It should be stored for no longer than four hours.

Warming prepared formula safely

Formula can be heated by placing the bottle in a container of hot water.

Microwaves can heat unevenly. If you are using a microwave, shake the milk thoroughly after heating and leave it to stand for two to three minutes. Shake the formula again before using.

Test the temperature of the milk by shaking a few drops onto the inside of your wrist. The formula should feel comfortably warm to the touch.

Throw out any formula that is left in the bottle after a feed.

Do not reheat any prepared formula that has already been warmed or partially consumed.

Handling prepared formula safely when travelling

If you need to take a bottle of formula with you when travelling, take previously boiled and cooled water separate from the formula powder.

Measure the water into a clean container or the baby’s bottle. Until your baby is three months old, you also need to sterilise this container.

Carry the measured formula powder in a clean and sterilised container.

Prepare the formula just before using it, following the steps outlined above.

Managing allergens when preparing milk

Take care when preparing formula or expressed breast milk for infants who have allergies. It is important to ensure there is no cross contamination of potential allergens.

Some precautions include:

• prepare the expressed breast milk or formula for infants with allergies first or in a separate area

• ensure hands, utensils and the preparation area is cleaned thoroughly before preparing milk for infants with allergies

• ensure hands, utensils and the preparation area is cleaned thoroughly between preparing each infant’s milk

• ensure allergic infants have their own individual cup or bottle which is not shared with others.

Related pages

Soy-based infant formula

Baby’s bottles and bisphenol A

Warming infant formula

Food and Nutrition Guidelines for Healthy Infants and Toddlers (Aged 0-2) [Ministry of Health]

Page last updated January 2009