It was bound to happen sooner or later, right? Take an already curvy girl and add a baby. Those girls and going to grow. Some women say that that was the first sign that they were pregnant, before they even took a pregnancy test. Other women can go through their whole pregnancy in the same bra size. But this isn't going to happen with Kim. Nope.
It must be terribly uncomfortable to exercise in clothing that is too small and doesn't contain your chest. She wouldn't be able to do anything high impact or hell, even walk on a treadmill without proper support. It would be painful and uncomfortable.