Feeding your baby formula

Infant formula is produced in hygienic and carefully controlled conditions, but it is not sterile. It can contain low levels of bacteria. Preparing formula correctly can minimise the growth of harmful bacteria, and help stop your baby from getting sick.

Buying and storing formula

If you decide to feed your baby formula, then infant formula is the only suitable choice.  Infant formula will provide your baby with all the nutrients required for normal growth and development until other foods can be introduced – around 6 months of age.

Before buying or using formula, check the use-by date. We also recommend checking the packaging for any signs of tampering.

 Video – checking for tampering

New Zealand has one of the most advanced and secure food safety systems in the world. All New Zealand formula producers use manufacturing systems that meet strict safety standards.

[A dairy tanker truck drives past grassy fields. The truck driver locks a hose onto a silo to transfer milk to the tanker. The driver opens panels on the truck to a machine where he connects and fills sample bottles.]

Dairy companies also test for quality and nutrition throughout the manufacturing system.

[Milk moves quickly through a factory pipe. Large bags of powdered infant formula move through a packing system.]

Infant formula and other formulas are usually sold in tamper-evident packaging. Tamper-evident means packaging is designed to protect the formula and help you tell if someone has opened or interfered with the packaging.

This video tells you about some of the common tamper-evident packaging used by infant and other formula manufacturers, and what to look for.

When checking for tampering, remember that not all products and brands are the same. If a product looks damaged or strange, check the packaging against others of the same type to see if they match. Turn the product over and check the base for any signs of tampering.

If you find a package that appears to have been tampered with, don't use it. Keep the package and call the Police on 0800 72 36 65.

If you have any health concerns, call Healthline on 0800 61 11 16.

Generally cans have a plastic lid covering a foil seal. Some foil seals may have a pull tab for opening. Some cans may also have clear plastic film over the plastic lid. Check all these areas for tears, rips, holes, or other punctures.

Check the base of the can. Look for any significant bulging of the seals or of the can. This can indicate tampering.

Sachets are sold individually, or in a cardboard package with individual foil sachets inside. If bought in a cardboard package, check it for unusual holes, tears, rips, or damage. Check each sachet. If any are broken, torn, are swollen or bulge abnormally, have holes, or leak formula when shaken or squeezed, don't use them.

Liquid formula can be sold in plastic bottles with foil seals, plastic screw-top lids, and may be covered in clear plastic film. Check all these areas and the base of the bottle for tears, rips, holes, or other punctures. Look for any significant bulging of the seals or of the bottle. This can indicate tampering.

You can find additional information by watching our video about the security measures that protect New Zealand infant and other formulas at every stage.

Remember, if you find a package that appears to have been tampered with, don't use it. Keep the package and call the Police on 0800 72 36 65.

If you have any health concerns, call Healthline on 0800 61 11 16.

For more information, call the Ministry for Primary Industries on 0800 00 83 33.

Download a factsheet on how to check for tampering [PDF, 578 KB]

Soy-based formula

The New Zealand Ministry of Health does not recommend soy-based infant formula for general use. This is because some health practitioners are concerned that phytoestrogens in soy-based infant formula may affect infants' developing endocrine systems.

There are some conditions, such as galactosaemia, where soy-based infant formula may be an appropriate choice. You should discuss this with your doctor or health professional.

Homemade formula

The New Zealand Ministry of Health advises parents not to use homemade infant formula (formula not commercially prepared).  There is a risk that homemade formula will not meet the nutritional needs of your growing baby, or may contain harmful levels of some nutrients.

Unsafe preparation can also contaminate the formula with bacteria that cause food-borne illness (food poisoning).

Storing powdered formula

Store powdered formula in a sealed container in a cool, dry place, and use within 4 weeks of first opening.

Storing prepared formula

You should prepare only as much formula as you need for each feed. If you need to store formula, you can keep it in a fridge for up to 4 hours. The fridge temperature must be less than 4 degrees Celsius. It's recommended you store prepared formula at the back of your fridge, where it's coldest.

Preparing powdered formula

Before preparing formula, make sure all feeding equipment has been cleaned – and sterilised if your baby is less than 3 months old. You should also make sure the area where you'll be making up the formula is clean.

Follow instructions

Always follow the manufacturer's instructions when preparing formula and use this checklist:

  1. Thoroughly wash your hands with soap and water and dry them well on a clean towel.
  2. Use correctly prepared water to make up formula. For at least the first 3 month of your baby's life, all water (including bottled) must be boiled on the day it's used. All tank or bore water given to babies and toddlers (up to 18 months) should be boiled and cooled.
  3. To prepare water for formula:
    1. Bring it to a rolling boil on the stove. If using an automatic kettle, wait until the kettle turns itself off.
    2. Keep boiled water covered while it cools. Then place put it in a sterilised bottle or jug. Cover and cool to room temperature before using. This water can be kept, covered, at room temperature for up to 24 hours.
  4. Following the product instructions, first add the correct amount of cooled, boiled water to a clean bottle. The bottle should be sterilised if your baby is less than 3 months. Then use the supplied scoop to add the correct amount of powdered formula. Never use more powder or less water than recommended and never add other ingredients to the formula feed.
  5. If possible, make up the formula just before you feed your baby. Throw away prepared formula that has been at room temperature for more than 2 hours.

Warming prepared formula

To warm prepared formula, place in a bowl of hot water. When ready, shake the bottle thoroughly to ensure the formula is an even temperature. Never reheat previously warmed or partly used feeds.

Always check the formula is at the right temperature by shaking a few drops onto the inside of your wrist. If the milk feels comfortably warm on your skin – not hot or cold – it's about the right temperature.

Electronic bottle warmers

You can buy electronic bottle warmers to heat up baby formula. These can warm bottles within a few minutes. Electronic baby bottle warmers are safe to use as long as you follow the manufacturer's instructions.

Ideally, choose a warmer that sounds an alarm and switches itself off when the formula reaches the right temperature. Always shake the bottle once warmed, and check the formula temperature before giving it to your baby.

Other bottle warmers

Some models of baby bottle warmers heat the formula or milk in other ways, for example, using a reusable warmer pouch, or a car battery as a heat source.

These products are safe to use as long as you:

  • make up the formula just before warming
  • remove the formula from the bottle warmer and finish feeding your baby within hours
  • throw out any unused formula.

Using a microwave

We don't recommend using a microwave to warm formula, as it can unevenly heat or overheat the formula. Overheating can cause burns to your baby's mouth and throat.

If you must use a microwave, you should:

  1. stop the microwave halfway through heating, remove the formula and shake it thoroughly. Then return to the microwave to finish heating
  2. let the formula stand for 2 to 3 minutes after heating
  3. shake the bottle then check milk temperature on the inside of your wrist before giving it to your baby.

Preparing baby formula when travelling

Don't make up formula until you're ready to use it. When travelling, you should:

  • carry measured formula powder in a clean and sterilised container
  • take water that has been boiled and cooled in a separate container from the formula.

Prepare the formula as you would normally, just before using.

Feeding babies with allergies

Take extra care when preparing formula for infants with allergies to make sure there is no cross-contamination of potential allergens.

If your baby has allergies you should take these extra steps:

  • Prepare their formula or expressed breast milk in a separate area, or before you prepare a feed for any other infant or child.
  • Ensure hands, utensils and the preparation area are cleaned thoroughly.
  • Ensure infants with allergies have their own individual bottles or cups.

You can buy specific formula for infants who are allergic to cows' milk or are lactose intolerant. You should use these instead of soy-based infant formulas. Discuss what formula you should feed your baby with your doctor or health professional.

Find out more

Who to contact

If you have questions about feeding your infant safely, email info@mpi.govt.nz.

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