When does my baby need fluoride and how can I tell if he's getting the right amount?

Your baby's developing teeth can benefit from a little fluoride. This mineral helps prevent tooth decay by strengthening tooth enamel and making it more resistant to acids and harmful bacteria. Most municipal water supplies are fortified with fluoride (you can call your local water authority to find out about yours). Bottled water suppliers can also tell you about the fluoride content of their water.

If you get your water from a well, you might consider buying a test kit from your local health department, a hardware store, or a pharmacy. If the results show a fluoride content of less than .3 parts per million, ask your child's doctor whether you should give your child a fluoride supplement (the amount recommended for children under 3 is .25 milligrams per day). She can prescribe fluoride in the form of drops that you can add to your baby's bottle or cereal once a day. The American Academy of Pediatrics doesn't recommend fluoride supplements for babies under 6 months old.

If you live in an area with fluoridated water, your child will get no fluoride from your breast milk, but he will get it from the water you use to make his formula if that water contains fluoride. Bottled water and fruit juices may contain fluoride, although the amount is rarely listed on the label.

A little fluoride is a good thing for your baby's teeth, but too much of it can lead to a condition called fluorosis, which in mild cases causes white spots to show up on your child's adult teeth. The American Academy of Pediatric Dentistry recommends waiting until your child is 2 to use fluoridated toothpaste, and even then you should let him use only a tiny (pea-sized) amount each time. This is because young children tend to swallow their toothpaste rather than spit it out and swallowing too much toothpaste over time can lead to fluorosis.