Formula Feeding Your Preemie

A beautiful 28 year old woman holding and feeding her sleeping 2 days old daughter.

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Premature infants (preemies, as they're affectionately known), might start off on a preemie formula that's specially tailored to their needs. There are many infant formulas on supermarket shelves which may leave new mothers confused about the best product for premature babies. Choosing a formula is definitely a decision that should be made with your neonatologist or pediatrician.

After finding the right formula, parents may wonder how long should their preemie be on it and when should they switch back to regular formula, un-supplemented breastmilk, or cow's milk? Learn about the distinct nutritional needs of preemies and how you can provide for them to give them the healthiest start possible.

Preemie Formulas in the NICU

For many babies born prematurely, feeding can be a challenge. They may not yet be able to perform the sucking motion or have the overall strength and coordination to bottle-feed or breastfeed. Preemies may also have an immature gastrointestinal (GI) tract, so their bodies may not properly break down milk proteins to absorb vital nutrients. Some preemies have GERD or acid reflux, causing them to spit up large amounts of formula or breastmilk.

Without feeding adjustments, these conditions can severely affect a premature baby's overall nutrition and growth. To ensure babies in the Neonatal Intensive Care Unit (NICU) are properly nourished, NICU staff the following methods to feed preemies who are not breastfeeding.

  • Bottle-feeding: once the baby is strong enough to coordinate the motions of sucking, swallowing, and breathing
  • Feeding tube: supplies necessary nutrients through a thin tube inserted either directly into the baby's stomach (gastronomy tube), through their nose to their stomach (nasogastric tube), or through the mouth to the stomach (orogastric tube)
  • Intravenous line (IV): supplies fluids and nutrients to the baby directly into their bloodstream

Premature babies and low birth weight babies often need special formulas to meet their nutritional needs and to catch up on their growth. Preemie formula and human milk fortifiers have more calories, protein, vitamins, and minerals than regular baby formula or breast milk, and are designed to help underweight babies grow faster.

In order to help preemies have good catch-up growth, doctors may tell parents to feed their babies special preemie formulas at home or to mix powdered human milk fortifiers (HMF) into their breast milk.

Common preemie formulas include NeoSure (by the makers of Similac), EnfaCare, Enfamil Premature LIPIL, and Nutriprem 2 (by Cow & Gate), and Similac Special Care. When preemies first take formula feedings, doctors start with small amounts of formula at a calorie ratio that mimics breast milk. As babies gradually adjust to feedings, doctors may introduce higher-calorie formula to help them grow more quickly.

Post-Discharge Preemie Formulas

NICU doctors determine when a preemie or low-weight baby is ready to leave the hospital once they meet certain developmental milestones. Once the baby has been discharged, parents have a few different feeding options available for their baby.

They can feed formula exclusively, combine formula and breastmilk feeding, and add human milk fortifiers to breastmilk for increased protein, calcium, and other nutrients. It's always best to follow the doctor's recommendations for low-weight and premature babies with unique nutritional needs.

Premature babies typically transition to a preemie discharge formula before going home. These include products like Similac Neosure, Enfamil Enfacare, and Cow & Gate Nutriprem 2. They have higher calories and more protein, vitamins, and minerals than regular infant formulas, so that catch-up growth started in the hospital can continue past discharge.

Preemie Formulas for Digestive Difficulties

Premature babies with certain digestive issues or food allergies may benefit from changing their usual formula to a different blend. 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 not be able to break down even the predigested proteins found in hypoallergenic formulas. For these infants, a formula that contains free amino acids (the building blocks of proteins) may be the only option. These products, such as EleCare, Enfamil Nutramigen AA, and Neocate, are lactose-free and may contain special fats for children who have difficulty absorbing fats from regular formulas.

Hypoallergenic Formula

Some babies are allergic to both cow's milk proteins and soy proteins. Hypoallergenic formulascontain pre-digested proteins, so babies who are allergic to milk proteins are usually able to tolerate hypoallergenic blends. Babies with GI conditions or food allergies may benefit from a hypoallergenic formula like Similac Alimentum or Neocate Infant products.

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 be fussy or cry excessively. Lactose-free formulas like Similac Sensitive or Enfamil A+ Lactose-Free may help these babies cry less and feel more comfortable.

How to Choose a Preemie Formula

Preemie formula is designed to provide all the protein, vitamins, and minerals the baby needs to catch up on growth and development.

The best formula feeding plan for your preemie will depend on their overall development, unique dietary and nutritional needs, and any food allergies they may have. Discuss these factors with your NICU team and 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. Or, you may just want to see if your baby prefers a different product. Don't switch baby formula until you've spoken with your doctor.

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 is 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 baby formula.

  1. Wash your hands.
  2. Clean and disinfect any equipment, including preparation surfaces, bottles, and nipples.
  3. Boil water (even if it is 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 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 is so 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 recommends NeoSure, EnfaCare, Nutriprem 2, or human milk fortifier, it's important to keep using them for as long as your doctor recommends.

Depending on your baby's unique needs, that may be until your original due date or until three, six, or even 12 months later, depending on when the baby achieves 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 or cow's milk. Because of the high calorie content, babies who use preemie formula longer than necessary risk obesity.

Hypervitaminosis D, a condition occurring when the body has too much of vitamin D, is another risk of prolonged use of preemie formula. Specific feeding plans will vary, as every baby has their own health needs and concerns.

Frequently Asked Questions

What baby formula is safe for preemie babies?

Several preemies formulas are available to meet the unique health and nutritional needs of pre-term and low-weight babies. Most regular preemies formulas are cow's milk-based. But lactose-free preemie formula and hypoallergenic formula are also available. Your doctor will recommend the best formula to ensure your baby gets all the calories, protein, and nutrients they need to catch up on their growth.

When will my preemie stop drinking formula?

While every baby's needs are different, most preemies use special preemie formula at least until their due date, and sometimes as long as three, six, or even 12 months after. From there, your doctor may recommend regular formula if they are under 1, or whole cow's milk if your baby is 1 or older.

How much formula should my preemie eat?

Babies have different nutritional needs. Consult with your pediatrician for the appropriate formula amount and feeding schedule based on your preemie's height, weight, and health concerns. Always prepare formula according to the product instructions and never dilute it to ensure your baby gets all of the calories and nutrients they need for catch-up growth.

A Word From Verywell

It can be scary and overwhelming to take a premature baby home from the NICU and be responsible for their care. But with support from your baby's doctors, you can find a formula feeding routine that works and provides all the nourishment they need to grow healthy and strong.

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Article Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Lubbe W. Clinicians guide for cue-based transition to oral feeding in preterm infants: An easy-to-use clinical guideJ Eval Clin Pract. 2018;24(1):80–88. doi:10.1111/jep.12721

  2. Demers-Mathieu V, Qu Y, Underwood MA, Borghese R, Dallas DC. Premature infants have lower gastric digestion capacity for human milk proteins than term infantsJournal of Pediatric Gastroenterology & Nutrition. 2018;66(5):816-821. doi:10.1097/MPG.0000000000001835

  3. Smollin C, Srisansanee W. Vitamin d toxicity in an infant: Case files of the University of California, San Francisco Medical Toxicology FellowshipJ Med Toxicol. 2014;10(2):190-193.doi: 10.1007/s13181-013-0365-0

Additional Reading
  • Cooke, R. "Nutrition of Preterm Infants After Discharge." Annals of Nutrition & Metabolism 2011(suppl 1): 32-36.
  • ESPGHAN Committee on Nutrition. "Medical Position Paper: Feeding Preterm Infants After Hospital Discharge." Journal of Pediatric Gastroenterology and Nutrition May 2006; 42, 596-603.