I've never been pregnant, but I've been so... um... equivalent cosmetically?... that I literally couldn't bend over and put my shoes on easily. When I was that way, I used slip-on ballet flats or jazz boots, but I know from recent pictures that the heels of ballroom are indubitably important. What about a dance sneaker? If it's not a 'permanent condition', you can always go back to 'real shoes' later.