Bottle Preparation

How to Wash and Sanitize Bottles

• Wash your hands with soap and water for 20 seconds before preparing bottles or feeding your baby. Clean and sanitize the space where you will be making the bottle.
• Clean bottles, nipples, and all utensils in hot, soapy water. Use a clean basin or container used only to clean infant feeding items. Do not wash directly in the sink because the sink may contain germs. Scrub inside and outside of bottles and nipples using a clean brush only used to clean infant feeding items. Rinse thoroughly with hot water.
• Rinse completely and allow to air dry on a clean, unused dish towel or paper towel. Do not rub or pat dry to avoid adding germs to your clean items.
• For extra protection, sterilize by placing bottles, nipples, and utensils in a pan of water and bring to a boil. Make sure all items are completely covered with water. Boil for 5 minutes. (A dishwasher may be used to sterilize in place of boiling water.) Air dry completely on drying rack, not with a towel.
  • You do not need to sterilize bottles, nipples, and utensils before each use unless there is a concern for contamination.

How to Prepare a Bottle of Expressed Breast Milk

If you plan to be away from baby for longer periods of time that will require you to miss a feeding, consider what method of breast milk expression is right for you: hand expression, single hand pump, or using an electronic breast pump.

Once you have expressed breast milk, follow these steps to safely prepare a bottle of breast milk:

• Wash hands and clean bottles, nipples, and all utensils in hot, soapy water. Use clean brushes to scrub inside and outside of bottles and nipples. Rinse thoroughly with hot water.
• Sterilize by placing bottles, nipples, and utensils in a pan of water and bring to a boil. Make sure all items are completely covered with water. Boil for 5 minutes. (A dishwasher may be used to sterilize in place of boiling water.) Air dry completely on drying rack not with a towel. You do not need to sterilize bottles, nipples, and utensils before each use unless there is a concern for contamination.
• If breast milk was just expressed it can be transferred to the bottle right away and does not need warmed or cooled.
• If breast milk is frozen, thaw by refrigerating overnight, running under lukewarm water, or placing in a container of warm water.
• If breast milk is thawed in the refrigerator, run under lukewarm water or place in a container of warm water.
  • Thawed milk should be used within 1-2 hours or placed in the refrigerator.
  • Thawed milk in the refrigerator should be used within 24 hours after is it thawed.
  • Never refreeze thawed human milk, even if it had been refrigerated.
• Milk should be gently swirled (not shaken) to mix it as it is normal for breast milk to separate.
• Before offering your baby expressed breast milk, test the temperature! To cool, hold the bottle under warm running tap water or place in a container of warm water. Breast milk should not be heated in the microwave because it can cause hot spots that may burn baby. Too hot, allow time to cool or place under cool running water.
• After feeding, throw out any leftover breast milk in the bottle or any breast milk that has been at room temperature for 1 hour or more.

Get more great breastfeeding information here!

How to Prepare a Bottle of Powder Infant Formula

Powder infant formulas are NOT sterile. Correct washing, sanitizing, mixing and storing are important when preparing bottles of infant formula.

• Wash your hands with soap and water for 20 seconds.
• Wash the top of the formula can before opening. Use one can of formula before opening another.
• Using washed and/or sanitized bottles and parts, mix powder formula according to the manufacturer’s instructions on the container.
  • If you have concerns about the safety of your tap water or if your baby was born prematurely or has a weakened immune system, you may want to boil the water before mixing with formula. See next section, When to Boil Water Before Mixing with Powder Infant Formula.
• Put a clean, sterilized nipple on the bottle (with nipple facing into the bottle) and shake gently until contents are well-mixed. Place a cap on nipple if not using immediately and refrigerate. Do not leave at room temperature and do not freeze formula. Use within 24 hours.

When to Boil Water Before Mixing with Powder Infant Formula

In most cases, it is safe to mix powder infant formula following manufacturer’s instructions. But if your baby was born prematurely or has a weakened immune system, you may want to boil water before using it to mix with formula.

• Boil water and let it cool to no less than 158°F / 70°C before pouring it into a bottle. Water should cool to this temperature within 30 minutes after boiling.
• Add the exact amount of formula listed on the container, and carefully shake the bottle rather than stirring the mixture.
• Immediately cool the formula to body temperature to ensure it is not too hot before feeding your baby. Run the prepared, capped bottle under cool water or place it into an ice bath. Do not let the cooling water get into the bottle or on the nipple.
• Before feeding the baby, test the formula’s temperature by putting a few drops on the inside of your wrist. It should feel warm, not hot.

Boiling the water is important for babies that were born premature or have a weakened immune system to protect against Cronobacter. Cronobacter is a germ found naturally in the environment and can live in dry foods like powdered infant formula. Cronobacter can cause diarrhea and urinary tract infections. Infection can be very serious for infants.

How to Prepare a Bottle of Liquid Concentrate Formula

• Wash your hands with soap and water for 20 seconds.
• Shake the can of liquid concentrate formula and wash the top of the can before opening. Use one can of formula before opening another.
• Using washed and/or sanitized bottles and parts, mix liquid concentrate formula with an equal amount of water.
  • Example A – Measure 4 ounces of formula into a clean bottle (use the ounce markings on the bottle) and add 4 ounces of water. (4 oz concentrate formula + 4 oz water)
    • Tightly cover opened formula cans and place back in the refrigerator right away. An opened can of liquid formula is safe in the refrigerator for up to 48 hours.
  • Example B – Pour one 13 ounce can of liquid concentrate formula into a clean pitcher (or other large container). Add 13 ounces of water. (13 oz concentrate formula + 13 oz water) Throw away empty formula can.

How to Prepare a Bottle of Ready-to-Feed Formula

• Wash your hands with soap and water for 20 seconds.
• Using washed and/or sanitized bottles and parts, place ready-to-feed formula in the bottle per instructions on the formula container. Do not add any water or additional powdered formula.
• An opened container of ready-to-feed formula is safe for up to 48 hours when tightly covered and refrigerated.

Feeding Other Liquids

Never give cow’s milk before 12 months. Why?

• Cow’s milk has too much protein, calcium, phosphorus, sodium, chloride, and potassium.
• Cow’s milk lacks key nutrients like vitamin C, vitamin E, linoleic acid, iron, and copper.
• Too much protein and minerals are hard on your baby’s kidneys, can cause dehydration, and it is hard for a baby to digest.
• Cow’s milk can cause bleeding from the intestinal tract.
• Bleeding caused by cow’s milk increases your baby’s chance of becoming anemic (or low in iron).

Never water down formula or breast milk. Why?

• You might be saving money, but you’re harming your baby’s health!
• Adding extra water decreases the nutrients your baby will get, slowing down their growth and development.
• Extra water also disrupts the electrolyte and mineral balance in your baby’s body which can lead to severe health problems, including seizures.
• Always mix formula according to manufacturer instructions.

Never make your own baby formula. Why?

• In the US, we have laws and regulations to make sure that infant formula sold in stores meets certain standards. Each formula must have a certain amount of each nutrient to help your baby grow healthy and strong.
• When making your own, you can’t be sure that you have enough of all of the right nutrients in the mixture OR you might end up with too much of a certain nutrient.
  • You might miss vital components like iron or vitamin C
  • You might have too much of a nutrient like salt which can harm your baby’s kidneys and liver.
• If your baby isn’t getting the right nutrients in the right amounts, they could have serious health issues for the rest of their life.

Sources: American Academy of Pediatrics (AAP) – How to Safely Prepare Formula with Water, Centers for Disease Control & Prevention (CDC) – Infant Formula Preparation and Storage, & CDC – Cronobacter Infection and Infants, AAP: Why Formula Instead of Cow's Milk, AAP: How to Safely Prepare Formula, AAP: Is Homemade Baby Formula Safe.