The other thing is, the round ligaments that support the uterus are also being stretched. This causes some rather sharp pains, particularly at night when I roll over. It often wakes me up if my husband doesn't when he tries to push me back onto my left side. FYI, sleeping on the left side is good for baby because it maximizes the amount of blood flow (oxygen, nutrients, life force) from mom.
I keep working out as much as possible, but sometimes things interfere (like the pool being closed indefinitely for repairs, or the aerobics instructor deciding not to show up to class). Having a backup plan for these days is the smart thing to do, but alas, I'm not so smart. Exercise is good for all these pains I'm having, though. And it keeps me from gaining weight too quickly (which I feel like I might be doing now) - finally gaining weight, and I still have to complain!
The really funny thing is that if I get super-excited (maybe during a highly-emotive football game) baby does too. So now all those stretches and burning sensations on the outside are mirrored with some little pokes and jabs from the inside. Gotta love it!