6. Warm the formula, if needed

It's fine to give your baby room temperature or even cold formula. If your baby prefers warm formula, place a filled bottle in a bowl of warm water and let it stand for a few minutes — or warm the bottle under running water. Test the temperature by putting a couple of drops on the back of your hand. The formula should feel lukewarm — not hot.

Don't warm bottles in the microwave. The formula might heat unevenly, creating hot spots that could burn your baby's mouth.

Discard remaining formula at the end of each feeding if it has been more than an hour from the start of a feeding. Resist the urge to refrigerate a bottle once you have fed your baby from it, since bacteria from your baby's mouth can still multiply in the refrigerator.