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Formula Feeding a Premature Infant

Parents choose to bottle-feed babies for many reasons. Here are some tips to help you feed your preemie with formula.

Newborn baby being bottle fed.

What kind of formula should I use?

Be sure to use the type of formula and the concentration that your baby's healthcare provider prescribed. Preemie formulas and "follow-up" formulas are specially made for premature babies. Some babies leave the hospital on regular infant formula. Other babies need a special formula that has more calories or certain nutrients. These may be better for your baby than regular formulas. Most babies should be taking formula with iron. Ask your baby's healthcare provider if you have questions. Always wash your hands and clean all work surfaces before prepping formula.

Preparing water for mixing formula

Use clean water from a safe source when preparing your baby's formula. Tap water is usually OK to use. You can check with your baby's healthcare provider or local health department to help determine whether your water supply is safe. Ask your baby's healthcare provider which type of water is best for your baby. They may recommend:

  • Tap water from your faucet

  • Bottled water that is labeled for infants and sterile

  • Tap or bottled water that has been boiled and then cooled

If using powder formula:

  • Follow the directions for mixing. Make sure you use the right amount of water and powder. Too much or too little water can cause diarrhea, constipation, dehydration, or other problems for your baby. Use the scoop that comes with the formula to measure the correct amount.

  • Put water in the bottle first, then the formula, and shake well to mix. Test the formula temperature to make sure it's not too hot before feeding it to your baby.

  • Use all the powder within 1 month after opening the package, or as directed on the package.

  • Keep mixed formula in the refrigerator when not in use. Don’t keep mixed formula for longer than 24 hours, or as directed on the package.

If using concentrated liquid formula:

  • Follow the directions for mixing. Make sure you use the right amount of water and concentrate. Too much or too little water can cause diarrhea, constipation, dehydration, or other problems for your baby.

  • Seal the package and keep it in the refrigerator after opening. Use within 48 hours of opening the package, or as directed on the package.

If using ready-to-feed formula:

  • Ready-to-feed formula does not need to be mixed. It's ready to pour right into your baby's bottle.

  • Seal the package and keep it in the refrigerator after opening. Use within 48 hours of opening the package, or as directed on the package.

If you don't refrigerate the prepared formula right away, use it within 2 hours of preparation and within 1 hour from when feeding begins. If your baby doesn't finish the bottle within 1 hour, throw away the unfinished formula. Don't use the leftover formula from a partly finished bottle.

Baby formula does not need to be warmed, but some caregivers like to warm their baby's bottle. Never heat a bottle of formula in the microwave. The liquid may heat unevenly and can burn your baby's mouth and throat. To warm a bottle, place it under warm (not hot) running water or in a cup of warm (not hot) water. Put a couple drops of formula on the back of your hand to make sure it’s not too hot. It should be lukewarm.

How do I know when my baby needs to be fed?

Look for and learn your baby’s feeding cues. Feeding cues are signs that your baby is hungry. Get to know your baby’s cues. Feeding cues may include:

  • Rooting. This is when your baby turns their head toward anything that touches their cheek or mouth.

  • Sucking movements or sounds.

  • Putting their hand to their mouth.

  • Crying. This is a late feeding cue. Try to feed your baby before they start to cry.

If your baby is feeding less than the advised amount, or not gaining weight on schedule, tell your baby’s healthcare provider.

Caring for bottles and other equipment

Bottles and all infant feeding items, such as nipples, caps, rings, valves, brushes, and wash basins, should be cleaned after every feeding. Follow these recommendations for cleaning your baby's feeding items:

Cleaning items using the dishwasher (if dishwasher-safe)

  • Take apart all bottle parts and all feeding items under running water before you place them in the dishwasher.

  • If possible, use a hot water setting and a heated drying (or sanitizing) setting.

  • Wash your hands with soap and water before removing the items from the dishwasher.

  • If items are not completely dry, air-dry them by placing items on a clean dish towel or paper towel. Don't pat-dry items with a dish towel. This may transfer germs to the items.

  • Once the items are completely dry, put them back together and store them in a clean area.

Cleaning items by hand

  • Wash your hands with soap and water .

  • Take apart all bottle parts and rinse all feeding items under running water. Don't set items in the sink.

  • Wash all items in a clean basin used only for infant feeding items. Fill the basin with hot water and add soap. Scrub the items with a clean brush used only for infant feeding items. Squeeze water through nipple holes.

  • Rinse all items again under running water.

  • Air-dry all items by placing them on a clean dish towel or paper towel. Don't pat-dry items with a dish towel. This may transfer germs to the items.

  • Wash the wash basin and brush after every use. You can wash them in the dishwasher (if dishwasher safe) or by hand with warm water and soap. Allow them to air-dry after each use.

  • Once the items are completely dry, put them back together and store them in a clean area.

Note: There is no need to wash the scoop for powered formula unless it becomes wet or dirty, such as falling on the floor. If the scoop needs to be washed, clean it as you would clean your baby’s bottles. Completely dry the scoop before putting it back into the container.

Your baby's healthcare provider may recommend sanitizing your baby's feeding items. Follow each item's manufacture guidelines for sanitizing your baby's feeding items.

Ask your healthcare provider:

  • What formula should I feed my baby? ________________

  • How often should I feed my baby? ________________

  • How much should I feed my baby?

    • At each feeding ________________

    • Total each day ________________

  • How much weight should my baby gain per week? _____________

  • How should I clean my baby's feeding items? _____________

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.