Supplemental Feeding: What and Why

When it comes to feeding your baby, breast milk is always best. It contains all of the nutrients your baby needs to grow, along with substances that help boost baby's immune system and protect against infections.

But sometimes babies have trouble nursing or need extra nutrition. In those cases, your doctor might recommend adding formula or fortifying your breast milk.

Premature or Low-Birth-Weight Babies

Any baby who is born before the 37th week of pregnancy is called "premature" or "preterm." These babies are usually smaller than a full-term baby and have special feeding needs.

The more premature a baby is, the more help they will need to eat. Babies who are born before 34 weeks may not be able yet to suck and swallow milk from their mother's breast. To start, they may be fed through a vein. They'll get a fluid mix that contains sugar, protein, fat, vitamins, and minerals to help them grow.

As babies get bigger, they can take breast milk or formula through a small tube inserted through their nose or mouth into their stomach. This is called gavage feeding.

Trouble Latching On

Babies who are born early have more trouble suckling and swallowing -- actions that they need to master so they can nurse. Sometimes even full-term babies can't quite latch on to their mother's breast.

If the baby is having trouble nursing, you can pump breast milk or supplement with formula. To feed a baby who can't latch on to the breast, you can use a bottle, spoon, medicine cup, or syringe.

Other Reasons to Supplement

Your doctor might also recommend supplementing breast milk with formula or switching over to formula if your baby is in one of these situations:

  • Low blood sugar
  • Dehydrated
  • Loses too much body weight
  • Has a high level of jaundice
  • Can't get enough nutrition because they are not nursing well or you aren't producing enough milk

Supplement Options

Many premature babies can tolerate breast milk. In fact, it's an ideal source of nutrition. Yet for babies who are born very small, breast milk might not be enough. Here are a few other feeding options your doctor might recommend.


Fortifiers. Babies who are premature or born at a very low weight -- less than 3 1/2 pounds -- may need extra nutrition. To make sure your baby is growing quickly enough, your doctor might recommend adding a liquid or powdered fortifier to breast milk. Fortifiers contain:

  • Extra calories
  • Vitamins
  • Protein
  • Minerals

Preterm formulas. For babies who were born early and aren't able to breast-feed, doctors often recommend a formula made specially for premature babies. These formulas are higher in calories than breast milk. They also contain:

  • Extra protein
  • Vitamins
  • Minerals

Special formulas. Babies who are allergic to milk proteins may need a special formula that contains broken-down versions of these proteins. There are also formulas for babies who have trouble digesting or absorbing nutrients from food.

Moving on From Supplements

While the baby is getting supplemental feedings, it’s a good idea for mom to pump their breast milk so they can start nursing as soon as their baby is ready. Once baby's growth has caught up, they may be able to switch them to breast milk.

WebMD Medical Reference Reviewed by Dan Brennan, MD on January 14, 2020



American Academy of Pediatrics: "Caring for a Premature Baby."

LaHood, A. American Family Physician, Oct. 15, 2007.

Pediatric Advisor 2013.3: "Premature Baby: Hospital Care."

The Academy of Breastfeeding Medicine Protocol Committee: Breastfeeding Medicine, November 2009.

Stanford School of Medicine: "ABCs of Breastfeeding."

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