Wow - those are such a bad idea!  The uterus will shrink on it's own, the best things to do for that are to 1.breastfeed (the natural oxytocin produced shrinks the uterus), 2.lightly self massage the fundus, 3. let nature take it's course.

Wearing the equivalent of a back brace/girdle 24/7 for 40 days is nuts!  The only thing that will do is cause your muscles to weaken because you're relying on the brace to support your abdomen and back.  And when your muscles are flabby, your belly will be flabby, too.  It probably makes you look sucked in under clothes, but that's about it.  Certainly isn't going to make you look like Brooke Burke.