I went to WDW when I was 6.5 months pregnant with DS. I did the same as some others on here have mentioned - basically avoided anything with a height requirement, with the exception of Soarin, as it is very gentle. I also did ride the Safari - the CM at the loading area was not very happy about it, but I actually did not find it to be very bumpy at all. Maybe I'm just too used to driving over our snow covered roads here at home, lol!
The biggest issues for me were the time on my feet, and the heat. We were there in June, and it was brutal, even though we took a break in the room every afternoon. I also have rheumatoid arthritis, and couldn't be on my meds while pregnant, so my feet were in pretty rough shape. We were there with my ILs on that trip, and they actually encouraged me to get a wheelchair. DH thought that was silly, and I was far too stubborn. But afterwards, I realized I probably should have just done it anyway, it would have made the trip more enjoyable. (Still had a great time, but would have suffered a lot less!)
Obviously it's worth checking with your doctor, but remember that they are people too, with their own biases. Ask 10 doctors the same question, you may get 10 different answers. So, consider their opinion, but your own knowledge and common sense counts for something too.
