My wife was 7/9 months pregnant (she's due next week) when we went to US last month so I should be able to give you a few tips.
Almost all of the rides have warning. Obviously some warnings are to be heeded (ie, rollercoasters) some are just there to protect US from frivolous lawsuits. Anyway this is a list of what she went on:
* - Shrek - no problem - they have a big warning out front but she was fine on it.
* Jimmy Neuton - don't go on it if your getting big. Ironically, there were no warning signs posted (that we saw anyway) on this one but this was the only ride my wife had problems on. The problem is the lap bar was too tight and can't be adjusted. She was very unconforatable the whole ride.
* - MIB - no problem
Other advice:
* Jaws - no problem
* Back to the Future - we avoided this one.
Of course, you can see all the shows with no problem.
Enjoy,
Bryan