I was right at 3 months pregnant when we went in May. It was unseasonably HOT! I took it easy, sat in the AC while DBF and DS rode the fun rides, drank lots of water. The only thing I can say is keep a map handy. You will find bathrooms you never knew existed! Just go slow and drink lots of water. Check with your OB to make sure you are safe to go. Mine said I was fine, to just take it easy, but have fun. There is still a lot you can ride. Follow the suggestions and if you feel uneasy then just sit them out. Here is something that someone posted for me when I was asking about it:
You can look at the park maps for the attractions with warnings - they are marked with a red triangle on the map and also on a sign at the entrance to the queue. This list of rides with warnings is taken off the park maps:
For Epcot here are the attractions with warnings:
Mission Space
Test Track has several quick stops and at the end, you go around a banked track at over 60 mph.
Note: Maestrom is not listed by WDW as having any warnings. It does have a drop, but the drop is not high speed or steep.
For Magic Kingdom:
Splash Mountain
Big Thunder Mountain Railroad
Tomorrowland Indy Speedway (the reason for this is the high likelihood of getting hit from the rear - it happens frequently). In addition, the little cars have gas engines and it does smell very gas-sy.
Space Mountain
Goofy's Barnstormer (this doesn't have a triangle warning on the map, but does have a sign that says pregnant women should not ride)
For Disney Studio
Star Tours is a rough simulator ride - you are on a spaceship that ends up in the hands of a 'rookie' driver. There are sudden stops and changes of direction. It is very rough.
Rock N Roller Coaster
Tower of Terror
For Animal Kingdom:
Kilimanjaro Safari
Kali River Rapids is a boat that is free floating during part of the ride. There is one very large, steep drop and some not so steep drops. You can get bumped around a lot as your boat bumps against the side of the 'river'.
Expedition Everest
Primeval Whirl
Dinosaur
The Safari and Kali River Rapids are listed because you can get unexpected hard bumps and drops during the course of the ride.
I hope you find it as helpful as I did. And remember to have fun!