I dont know about doing it while preganant but once you can do it go to the dentist and ask them for the "Night White" tubes...about $40. I had tried all the otc ones, colgate, ect ( I drink coffee like it is air!) and none of them did anythign really, felt I wasted my $$. These work wonderful!!! Well worth the little extra that they cost. I went to the expense of getting teeth molds but my mother uses either a sports mouth guard or a piece of saran wrap over her teeth when she uses it and both of our teeth are super super white...people even stop and ask me! Also I brush with hydrogen peroxide once a day..just put it on your toothbrush and brush for 2 mins, I dont rinse but let it sit for a bit, like 10 mins before rinsing.