I think the recommendation is med-well to well done so that bacteria can all be killed. I have just avoided steak because I like mine med-rare and there is no way I'm going to ruin a steak by eating it med-well, haha.
Pregnant or not I've always ate mine medium rare. I have 3 healthy kids and #4 on the ways.
I was told Medium-well is the minimum to eat. Since at that temp the bacteria is dead.