Good question...I wonder if there is a list somewhere?? It would suck to think that something was prolly okay and then get there and see the "pregnant women should not ride" signs.
I'd go on Soarin' myself. It's not a rough ride so isn't likely to hurt baby. Frankly I'm not sure any of the ones I've been on would make me worried and likely to sit them out, but then our kids are small and we've passed over all the "intense" rides so far. Hoping to get to experience some of the on our upcoming trip.
I totally stole the following from this website:
http://www.passporter.com/wdw/pregnant.htm
I don't know how old this is, cause I've never even heard of Body Wars

and I'm thinking that some of the MK listings would be fine, but then I guess it all depends on how each person feels with each pregnancy.
6. Avoid attractions with health restrictions. These restrictions are always posted at the attraction itself, or you can check the PassPorter Walt Disney World guidebook to find out before you go. In general, you want to avoid rides that are bumpy, cause dizziness, or accelerate too quickly. Epcot is the most pregnant-friendly park -- only two attractions, Test Track and Body Wars, are off-limits. At Magic Kingdom, just say no to Big Thunder Mountain Railroad, Splash Mountain, Dumbo (if you get nauseous easily), Magic Carpets of Aladdin, Mad Tea Party, The Barnstormer, Astro Orbiter, Space Mountain, and the Tomorrowland Indy Speedway. At Disney-MGM Studios, stay off Star Tours, Rock n' Roller Coaster, and the Tower of Terror. At Disney's Animal Kingdom, avoid Kali River Rapids and Dinosaur. Kilimanjaro Safaris carries a health restriction, but many pregnant women (including Jennifer's sister) feel okay about it. If you decide to go on the Kilimanjaro Safaris, ask the cast member if you can ride in the wheelchair-accessible vehicle -- it isn't as bumpy as the others. If you're not certain if a particular ride is for you, have your significant other try it out first and then report back. If you opt out of a ride, you can either shop in a nearby gift shop (there's always one around) or stay in the queue with your party until boarding and then ask for the "chicken exit."