Kilimanjaro Safari's is fine for the most part. If you don't want to be bumped around too much request the front row of seats. I'd probably skip it later on in pregnancy though....wouldn't be comfortable and might be enough to break the water bag if its already reached its limits! I did ride it during pregnancy several times...all in the first and second trimester.
As far as waterslides...I've also heard that pregnant women shouldn't ride them. They say there is the possibility for air to be forced up the birth canal, which can kill you. Then again, you may want to ask your midwife or ob if this is really true. Its not something I ever inquired about. I'm not a huge fan of waterslides anyway.
When I went to WDW at approx. 5 weeks pregnant I pretty much rode everything...figuring it would be entirely possible for me to not know I was pregnant at the time and with the baby the size of a grain of rice, he was pretty well protected. When I was at WDW during my second trimester (during 2 of my pregnancies) I just skipped the "thrill" rides. I still did Kilimanjaro. I think I skipped anything that had restraints that my belly would come into contact with too....like Kali River Rapids. The only other thing I rode that had a pregnancy warning I think was the Tomorrowland Speedway....and I had my dh ride in the car behind me so I knew I wouldn't get rear ended.
Most of the thrill rides probably wouldn't even hurt the baby...its the possibilty of being slammed hard into the restraints if anything goes less than perfectly during the ride. If they have to pull the emergency brakes on a fast ride its going to be a harder stop than on Winnie the Pooh.
Basically, use common sense and watch for warnings...also consult your pregnancy care provider. Also, I forgot to add....drink plenty of water and rest as you need to! Water is most important...dehydration can really mess you up during pregnancy!
