Warning signs will be posted at the applicable attractions. Most of them you can probably predict--any roller coasters, TOT, Star Tours, Kilimanjaro Safari, etc.
I'm not a doctor, although I am a father of two. You should DEFINITELY heed the warnings and restrictions. If memory serves, this early part of your pregnancy leaves you (or more specifically, your child) more succeptable to complications arising in the pregnancy. The last thing you want to do is risk your health, and the health of your unborn child, in exchange for a few thrills at Disney. Wait until the next trip for that.