Preparing infant formula powder: A safe and complete guide

Preparing infant formula milk powder requires care and attention to ensure the safety and nourishment of your baby. Following the correct steps in the preparation and storage of powdered milk is essential to prevent health risks. In this step-by-step guide we will look at how to safely prepare powdered milk, the best storage methods and useful tips on how and when to avoid some common tools, such as bottle warmers.

How to safely prepare infant formula powder

The preparation of powdered milk must follow a number of precautions, because even if sealed, powdered milk is not sterile and may contain bacteria, which, if not handled correctly, can cause very serious infections in the newborn baby. Safety relies above all on the use of water at an appropriate temperature (70°C) and the use of clean, sterilised tools.

Steps to prepare powdered milk safely:

1. Cleaning the work surface: Clean the surface you will be working on well to avoid contamination.
2. Hand washing and bottle sterilisation: Wash your hands thoroughly and use sterilised bottles and teats.
3. Preparing water: Boil 1 litre of drinking water (you can use tap water if it is safe where you live – there is no indication that bottled water is better) and let it cool for about 30 minutes until it reaches 70°C. Otherwise, use a clean kitchen thermometer.
4. Measuring the milk powder: Use the measuring cup provided in the package to dose the powder correctly, observing the indicated water/powder ratio to avoid risk. Level but do not crush the milk in the measuring cup.
5. Pour the water and add the powder: First pour the water into the bottle and then the powder; close and shake well to obtain a homogeneous mixture.
6. Cooling: Cool the bottle under a jet of cold water until it reaches a lukewarm temperature (approx. 37°C).
7. Temperature test: Before giving the bottle to the baby, test the temperature of the milk by pouring a few drops onto your wrist.

Liquid infant formula, on the other hand, is sterile until opened. Once opened, it should be stored in the refrigerator and consumed within 24 hours.

What is the best infant formula powder?

Nutritionally, all type 1 infant milks are similar and suitable throughout the first year of life. There is no scientific evidence showing benefits or disadvantages of one milk over another. If in doubt about the suitability for your child, consult your paediatrician or a lactation consultant.

Safe storage of prepared milk

It is always preferable to prepare milk powder just before use. If you need to take milk with you, follow these tips on what to bring:

• Measured milk powder carefully kept in a clean, dry container
• A thermos flask with water previously boiled and kept at 70°C
• A sterilised feeding bottle with teat and cap.

However, if it is necessary to prepare it in advance, it is essential to follow certain storage precautions:

• In the refrigerator: You can store the prepared milk for up to 24 hours at below 5°C.
• In a refrigerator bag with ice: Do not exceed 4 hours.
• At room temperature: Consume within 2 hours, then discard.

Remember that these recommendations are intended for when you have no alterative, they should never become routine. As an alternative, you can consider using liquid infant formula when you go out instead of powdered milk. 

To warm the prepared milk, place the bottle in a container of hot water and always check the temperature before giving it to the baby. Never use the microwave because it does not heat evenly and could cause burns to the baby.  

Important: Never store leftover milk after feeding, as contact with saliva can encourage bacterial growth so any leftovers should be thrown away.

Why avoid bottle warmers for powdered milk?

Bottle warmers, while convenient, often do not reach the 70°C necessary to kill possible bacteria in powdered milk, so it is not recommended to use a bottle warmer for this purpose. Instead, they are suitable for warming liquid milk that is already sterile at a lower temperature (about 37°C).

Calculating the right amount of milk according to weight and age

Calculating the right amount of milk to prepare is a major concern for parents. The amount of formula varies greatly according to the weight, age and needs of the baby. 

In addition, adjustments must be considered for mixed feeding: in this case, it is important to reduce the amount of formula milk from the standard, often available, chart to avoid overfeeding. The amount varies depending on how much breast milk the baby receives. I recommend that you consult a lactation consultant to customise the dosage and avoid overfeeding.

Final tips for preparing infant formula powder

• Recognise your baby’s cues: Every newborn baby has different needs. It is important to learn to recognise hunger and fullness cues. As with breastfeeding, every feed can be different and also with formula feeding you should respect your baby’s cues and timing. 
• Choose liquid milk as a practical option when you are away from home: It is a convenient option for immediate use.
• Avoid repeated warming: Warm the milk only once and store it safely.

The importance of breastfeeding and professional support

Breastfeeding remains the preferred option for infants, as it provides nutrients and antibodies that support the immune system and promote healthy, balanced development. However, formula feeding can be a valid and safe choice when necessary. Every mother and every child is unique and the choice of how to feed your child is personal and should be respected. Do not hesitate to seek support from a lactation consultant or paediatrician if you have any concerns about your baby’s nutrition.

For more information or to discuss your feeding options, contact me for personalised advice.