Despite popular opinion, pre-born babies cannot actually 'drain' the calcium out of your teeth and bones....my fave pregnancy book (Dr. Miriam Stoppard) states 'there is no way of extracting calcium from the teeth. However, the high levels of progesterone that are produced during pregnancy will make the margins of the gums aroudn the teeth soft and spongy, predisposing them to infection.'
I've been taking calcium supplements....big tablets but worth it I guess!