Some babies may actually prefer cold or room-temperature bottles to warm, especially if you start serving them that way from the get-go (which can make things easier for you in the long run). But if your baby does prefer a warm bottle, remember that the microwave can create dangerous "hot spots" in bottles, so you should never microwave formula.

Instead, you can:

• Run the bottle under very warm or hot water for a few minutes.
• Put your baby's bottles in a pan of hot water. Just be sure to remove the pan from the heat source before placing the bottle in it.
• Use bottle warmers that either sit on your countertop at home or plug into your car's cigarette lighter.

Whichever way you choose to heat your baby's bottles, be sure to shake the bottle vigorously. Then test the temperature of the formula by squirting a drop or two on the inside or your wrist before feeding your baby. It should be lukewarm (barely warm) not hot.

How long can I keep mixed formula in the refrigerator?

You should always refrigerate any bottles you fill for later feedings to prevent bacteria from growing. Throw away any mixed formula that's been stored in the fridge after 24 hours and any ready-to-feed formula after 48 hours.

How long can I keep a bottle of formula at room temperature before it goes bad?

Discard any prepared or ready-to-feed formula that's been sitting out after 2 hours.

Can I give my baby the same bottle of formula more than once?

No. Throw away any leftover formula because of the possibility of bacterial growth from the baby's mouth.