i am a hygienist....this whole idea that the baby can steal calcium from your teeth is totally untrue. what tends to lead to dental problems during pregnancy and after is just lifestyle changes. you have less time/energy to take care of yourself. take your vitamins, go get your cleaning, and brush and floss well daily and you wont have to worry. use sensodye if your experiencing sensitivity.
also-if you are experiencing ms, and throwing up, DO NOT immediately brush your teeth, sounds gross but it is pretty much just brushing stomach acid into your teeth and is very damaging. rinse with water and wait a little before brushing.
and flouride in water and toothpaste wont hurt you or your baby as long as you dont eat the entire tube of toothpaste