How To Add Formula To Breast Milk To Increase Calories (Milk Fortification & More About HMF)

Breast milk is the leading choice for optimal nutrition in newborns and infants. However, there are certain instances when breast milk may not be enough — for preemies, sick babies, and underweight newborns. Regardless, adding calories to milk should only be done when advised by a qualified healthcare provider. Increasing caloric intake with breast milk can be done using formula milk powder or a human milk fortifier (HMF). There are 24, 27, and 30 kcal/oz options for increasing calories in breast milk. Alternative ways to add calories are to mix breast milk or hard-boiled egg yolk with infant cereal, add pureed meat, or fruits and vegetables to your child’s diet, depending on how old they are.

Adding formula to breast milk

Indeed, breast milk is the best source of nutrition for healthy babies. It provides infants with natural antibodies to boost their immune systems against serious illnesses.

Milk helps strengthen the gastrointestinal tract by decreasing the chances of allergens and microorganisms triggering allergies and infections.

Compared to formula, breast milk is readily made and does not need to be paid for.

Unfortunately, there will be circumstances when breast milk may not be enough – not all babies are born completely healthy, and some may have medical issues requiring additional nutrient intake.

At the same time, parents shouldn’t consider increasing their baby’s caloric intake out of the blue just because they want to. In short, too much calories is not always a good thing.

When should milk calories be increased?

If your child was born preterm, your milk will most likely have high amounts of fat, protein, and some minerals, like sodium, during the first two weeks or so.

Over time, these nutrients will decrease as compared to that of term milk.

Because of this, preemies more often need supplementation to increase their nutrient intake.

A newborn baby is sleeping at the hospital after recently being born

Babies who are born very small (called very low birth weight or VLBW infants) are at risk of growth and neurocognitive problems. To develop well and catch up with normal-weight infants, these babies may also need fortified milk.

Some sick newborns, especially those with gastrointestinal issues, might need specialized formulas that involve milk fortification. This is to ensure they have the right amount of calories and minerals as they rebound from sickness.

Babies who find it difficult to gain weight might need fortification on a case-to-case basis as determined by your healthcare provider.

How do we add calories to breast milk?

One way to increase calories is to add human milk fortifier (HMF) to breast milk.

Different types of fortifiers are available, which differ based on the number or amount of nutrients included.

HMF may have various calorie formulations – 24 kcal/oz, 27 kcal/oz, and 30 kcal/oz.

Your doctor will evaluate and decide if your baby needs milk fortification and which HMF should be used.

A more accessible method is to mix breast milk and regular milk formula (in powder form). Again, this is not for healthy newborns and should only be done under the advice of a physician with experience in managing sick newborns.

Clean your hands with soap and water. Use sterilized containers, measuring cups, and make sure that your working surface is also clean.

Slowly warm breast milk to room temperature. Mix in the formula using the correct measuring spoon or scoop.

To make a 22 kcal/oz milk formulation, mix half a teaspoon of formula milk powder and 3 ounces of expressed breast milk.

For the 24 kcal/oz milk formulation, mix one teaspoon of formula milk powder with 3 ounces of expressed breast milk.

What are other ways to increase my baby’s calorie intake other than milk?

For babies who are given the go-signal to try complementary foods (usually 6 months and older), try iron-fortified baby cereals mixed with formula or breast milk.

Boil eggs and mix the yellow yolk with breast milk or formula. You can also mix 4 ounces of pureed food (poultry or meats) and a teaspoon of dry infant cereal.

Soft, pureed, or mashed fruits and vegetables may also be included in the meal.


Can I use a human milk fortifier even if my baby has a normal weight?

Your baby should be evaluated by a doctor first. Start HMF only when given medical advice to do so.

If HMF or other milk fortification products are misused, this could lead to problems in digestion in your child.

I have some leftover fortified breast milk. Can I still use this within the day?

If you mixed too much for one feeding, don’t put all of it in the milk bottle.

You can store extra fortified breast milk using a sterilized and well-sealed container in the refrigerator for up to 24 hours.

Leftover milk from the bottle (after feeding), on the other hand, should be thrown away.

Before the next feeding, warm the milk in a small basin with warm water, shake the bottle afterward, and check the temperature.


While breast milk is the best way to feed newborns and infants, this may be the exception in preemies and sick babies.

Increasing caloric intake can be done by mixing formula milk powder or HMF with breast milk under the guidance of a doctor.

If this is not possible for your child, there are still other ways to add calories without using breast milk or milk formula.

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Sarah is a healthcare writer, motivated by her love of reading books while growing up. She took up human biology and further studies in medicine, in order to fulfill her passion for helping kids. While she isn't a biological mother yet, she has taken two young dogs, named Indy and Obi-Wan, under her wing. She would love to someday travel the world and meet kids from different cultural backgrounds.

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