Formula Feeding Your Preemie

Premature baby being bottlefed formula at hospital
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Premature infants might need to start on a preemie formula that's specially tailored to help them grow healthy and strong. But it's hard to know what's best for your preemie as they progress from the neonatal intensive care unit (NICU) into different ages and stages. You may also be wondering when it might be OK to switch to regular formula, breast milk only, a combination of formula and breast milk, or cow's milk.

Learn about the unique nutritional needs of preemies and how the formula choices you make for them can give them the healthiest start possible. Although you should always be guided by a 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.

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 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 also have GERD or acid reflux, causing them to spit up large amounts of formula or breast milk.

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, through their nose (nasogastric tube), or through their mouth to their stomach (orogastric tube). Others have nutrients delivered directly into their bloodstream through an intravenous (IV) line.

According to the American Academy of Pediatrics (AAP), babies should be given breast milk, which has unique immune-boosting benefits, whenever possible. Often, fortifiers derived from human milk are combined with pumped breast milk to boost calories and nutrients. Recent research suggests human milk fortifiers might be safer and healthier for babies than cow's milk fortifiers.

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 formula and are designed to help underweight babies grow faster. Common ones for babies to receive in the NICU include Similac Special Care and Enfamil Premature.

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 usually determine when a preemie or low birth weight baby is ready to leave the hospital based on when they have met certain developmental milestones. Once your baby has been discharged, you have a few different feeding options for your baby.

If your baby is unable to get enough nutrients from breast milk alone, you can supplement breast milk feedings with formula for increased protein, calcium, and fat. Or, you can feed your baby with a doctor-approved formula for preemies exclusively. It's important to follow the doctor's recommendations for low birth weight and premature babies with unique nutritional needs.

Typically, preemies transition to a preemie discharge formula before going home. These include products like Similac Neosure or Enfamil EnfaCare. They have higher calorie counts and more protein, vitamins, and minerals than regular infant formulas, so that catch-up growth started in the hospital can continue at home.

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 free amino acids (the building blocks of proteins) may promote growth. These products include EleCare, Enfamil PurAmino, and Neocate.

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. In these cases, it's best to speak with your baby's pediatrician to determine which formula is best for your baby.

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. Babies with GI conditions or food allergies may benefit from a hypoallergenic formula like Similac Alimentum or Enfamil Nutramigen.

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

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 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 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. 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.

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 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 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 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 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 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 a premature baby formula, it's important to 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.

A Word From Verywell

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

If you choose to or need to feed your preemie formula, take care to consult a doctor on what kind and what amount is best for your baby. Regular check-ups and discussing each feeding transition will ensure your preemie continues healthy development through infancy and beyond.

Frequently Asked Questions

  • What baby formula is safe for preemie babies?

    Several preemie formulas are available to meet the unique health and nutritional needs of preterm and low-weight babies. Like other infant formulas, most preemie formulas are cow's milk-based. But lactose-free and hypoallergenic preemie formulas are also available. Your baby's 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 original 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 12 months, or whole cow's milk if your baby is 12 months 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.

12 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.
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  4. Eidelman AI, Schanler RJ, Johnston M, et al. Breastfeeding and the use of human milk. Pediatrics. 2012;129(3):e827-e841. doi:10.1542/peds.2011-3552

  5. Lucas A, Assad M, Sherman J, Boscardin J, Abrams S. Safety of cow’s milk-derived fortifiers used with an all human milk base diet in very low birthweight preterm infants: Part ii. Neonatol Today. 2020;15(10):3-8. doi:10.51362/

  6. U.S. Department of Health and Human Services. Transitioning Newborns from NICU to Home.

  7. Nemours Foundation. Taking your preemie home.

  8. Vanderhoof J, Moore N, de Boissieu D. Evaluation of an amino acid−based formula in infants not responding to extensively hydrolyzed protein formulaJ Pediatr Gastroenterol Nutr. 2016;63(5):531-533. doi:10.1097/MPG.0000000000001374

  9. Heine RG, AlRefaee F, Bachina P, et al. Lactose intolerance and gastrointestinal cow’s milk allergy in infants and children – common misconceptions revisited. World Allergy Organ J. 2017;10:41. doi:10.1186/s40413-017-0173-0

  10. Nemours Foundation Children's Health System. Formula feeding FAQs: Getting started.

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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.

By Cheryl Bird, RN, BSN
Cheryl Bird, RN, BSN, is a registered nurse in a tertiary level neonatal intensive care unit at Mary Washington Hospital in Fredericksburg, Virginia.