What To Know About Formula Feeding Your Preemie

Preemie formulas provide extra nutrients to help premature babies catch up on growth. Learn how to choose and use preemie formula (and when to stop).

Medically reviewed by Lyndsey Garbi, MD Medically reviewed by Lyndsey Garbi, MD

If you have a premature baby in the neonatal intensive care unit (NICU), your health care provider might recommend starting them on a preemie formula that's specially tailored to help them grow healthy and strong. But should they keep having preemie formula after they graduate from the NICU? You may also be wondering when it's OK to switch to regular infant formula, breast milk, or a combination of the two.

Although decisions regarding your preemie should always be guided by their neonatologist or pediatrician, it's important to understand why certain preemie formulas and feeding routines may be better than others—and when it may be time for a change.

manonallard / Getty Images
manonallard / Getty Images

Preemie Formulas in the NICU

For many babies born prematurely, feeding can be a challenge. They often lack the overall strength and coordination to perform the sucking motion necessary to breast- or bottle-feed. Preemies may also have an immature gastrointestinal tract, so their bodies may not properly break down milk proteins to absorb vital nutrients.

To get on a healthy growth track, many preemies in the NICU start out receiving formula or pumped breast milk through a thin feeding tube. These tubes are inserted either directly into their stomach or through their nose or mouth into their stomach. Others have nutrients delivered directly into their bloodstream through an intravenous (IV) line.

While breast milk has unique immune-boosting benefits, if you can't or choose not to breastfeed or pump breast milk, your NICU doctor will likely recommend a special formula to meet your preemie's nutritional needs. Preemie formulas tend to have more calories, protein, vitamins, and minerals than regular infant formulas and are designed to help underweight babies grow faster.

Post-Discharge Preemie Formulas

NICU doctors usually determine when a preemie or low birth weight baby is ready to leave the hospital based on when they meet certain developmental milestones. Once your baby has been discharged, you may have a few different feeding options, including breast milk, different types of infant and preemie formulas, or a combination of breast milk and formula.

If your baby is unable to get enough nutrients from breast milk alone, your baby's doctor may recommend supplementing breast milk feedings with formula for increased protein, calcium, and fat. Or, you may choose to feed your baby with a doctor-approved preemie formula exclusively.

It's also common for preemies to transition to a preemie discharge formula before going home. These preemie formulas have higher calorie counts and more protein, vitamins, and minerals than regular infant formulas, so the catch-up growth started in the hospital can continue at home.

Preemie Formulas for Special Dietary Needs

Premature babies with certain digestive issues or food allergies may benefit from special infant formulas. Here are some of the most common types of formula for preemies with special dietary needs.

Amino acid-based formula

Babies with severe stomach problems may be sensitive to most formulas. For these infants, a formula that contains amino acids (the building blocks of proteins) may help promote growth.

Lactose-free formula

On occasion, a baby may not have enough lactase, the enzyme used to digest the milk sugar lactose. Because these babies don't digest milk sugars well, they may experience uncomfortable gastrointestinal (GI) symptoms like stomach pain, bloating, gas, and diarrhea, which may cause them to be especially fussy or cry excessively. If your preemie has trouble digesting lactose, their health care provider might recommend a lactose-free formula.

Hypoallergenic formula

Some babies are allergic to both cow's milk proteins and soy proteins. Hypoallergenic formulas contain pre-digested proteins, so babies who are allergic to milk proteins are usually able to tolerate hypoallergenic blends.



Newborn check-ups are especially important for premature babies, so never skip a routine well-baby visit. Your pediatrician will want to regularly monitor your baby's weight, length, and other growth markers to make sure they are getting the nutrition they need.



How To Choose a Preemie Formula

Preemie formula is designed to provide all the protein, vitamins, and minerals a premature baby needs to catch up on growth. The best formula feeding plan for your preemie will depend on their overall health, unique dietary and nutritional needs, and any food allergies they may have.

Discuss these factors with your baby's neonatologist or pediatrician to determine the best preemie formula for your baby. The same is true if you want to change their formula. As your baby gains weight and gets stronger, their nutritional needs may change, but you shouldn't switch baby formula until you've spoken with a health care provider.

While different infant formula products serve different needs, all formulas sold commercially in the United States must meet the same nutrition and safety standards. Whichever formula you feed your premature baby, ensure it's safe by only buying products from reputable brands and retailers, checking the expiration date on the package, and looking for odd colors or odors that suggest the formula is expired or has been tampered with.

How To Use Formulas for Premature Babies

Because premature babies have strict dietary needs and are especially vulnerable to infection, it's important to follow the right steps to prepare your baby's formula:

  1. Wash your hands.

  2. Clean and disinfect any equipment, including preparation surfaces, bottles, and nipples.

  3. Boil water (even if it's bottled water).

  4. Let the heated water cool for approximately 30 minutes before pouring it into the bottle.

  5. Add the precise recommended amount of water and formula to the bottle.

  6. Assemble the bottle and shake it to dissolve the formula in the water.

  7. Run the bottle under cool water.

  8. Check the temperature of the formula to ensure it's cool enough before feeding your baby.

Remember that it's important for preemie babies to get all the calories and nutrients they can from their formula. For that reason, it should never be diluted.

When To Stop Using Preemie Formula

If your doctor suggests a preemie formula for your baby, keep using it for as long as they recommend. Depending on your baby's unique needs, that may be until your original due date or several months later. Often, doctors are looking for the baby to achieve catch-up growth (rapid growth marked by notable weight gain, height increase, and increased head circumference).

From preemie formula, your doctor may transition your baby to regular infant formula (if under 12 months) or cow's milk (if over 12 months). Specific feeding plans will vary, as every baby has their own health needs and concerns. Regular check-ups and discussing each feeding transition will ensure your preemie continues healthy development through infancy and beyond.

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