All of the "thrill rides" are pretty much off limit for pregnant woman. It is just a "suggestion", just like those with back problems, etc. But I would never risk it.
No Space Mountian, Big Thunder Mountian. Spash Mountian, Test Track, Tower of Terror, Rocking Rollar Coaster, Star Tours, etc.
Pretty much anything with a height limit is a big no no for pregnant woman. But you can go on all the other rides.