Brush your teeth with fluoridated toothpaste twice a day, and floss once a day. Rinse every night with a fluoridated, alcohol-free mouth rinse. Replace your toothbrush every 3 or 4 months or when you are sick. Do not share your toothbrush with others. After eating, chew xylitol-containing gum or mints to help reduce tooth decay-causing bacteria. If you vomit, rinse out your mouth with a teaspoon of baking soda and a cup of water to stop acid from attacking your teeth then wait 30 minutes before brushing.
For more information see http://www.mouthhealthy.org/en/pregnancy