DONT DO IT!!

im affraid to say that pregnancy has nothing to do with bad teeth! id go get a second opinion on whats wrong with your teeth and get things sorted so your painfree.

emmy has made excellent points, its not as easy as it seems! full uppers are easier than full lowers as the upper get suction, the bottom doesnt. your face will cave in and when your older people will be able to tell you have dentures, i honestly think youd find it hard to find someone willing to remove all your teeth at such a young age.
once there gone there gone!