There are some rides at WDW that do have posted warnings for pregnant women, as well as for guests with heart conditions, back problems and other medical issues. These warnings are noted on signage at the rides as well as on the Walt Disney World website. For example, if you look at the bottom of the Space Mountain page
HERE, you will see under "Guest policies":
- For
safety, you should be in good health and free from high blood pressure,
heart, back or neck problems, motion sickness or other conditions that
could be aggravated by this adventure.
- Guests must transfer
from motorized scooter or ECV to an available wheelchair, then from the
wheelchair to the attraction/ride vehicle.
- Expectant mothers should not ride.
You should know that there are very few rides at WDW that have these warnings and those that do are primarily thrill-type rides that have high speeds, bumps, or spins. Most of them also have height restrictions that would also make them off-limits for 4-year-olds.
All that being said, there is PLENTY for you to do at WDW in your situation. I visited Disney when I had a three-year-old and was five months pregnant with twins. On that trip, I was able to enjoy: Small World, Jungle Cruise, Dumbo, Peter Pan, Toontown, Country Bear Jamboree, character greetings, the Tiki room, meals, parades, fireworks, and MUCH more.
Another resource you should look for is a book called PassPorter's Open
Mouse for Walt Disney World. This is the definitive guide for anyone
visiting WDW with any sort of physical issue, including pregnancy. The potential challenges
with each attraction are described in great detail. You can get this
book at Amazon.com or from major booksellers.