Well, Congrats! It is a very exciting time to be pregnant and expecting a precious little one. I am a mother of 4 children. All I can say is if I were pregnant with my first, knowing me, I probably would have ridden. By the time I preg. with my second, probably not. But, when I was pregnant with my third and at Disney, I did not.
To me, and I don't know if you have children, but I became more worried and more cautious with my pregnancies with each one. As you look into your child's eyes, that are already here, you think "how could I have done anything so minor to have the possibility of hurting you?" When I was at Disney with my two oldest and preg with my third, I just kept thinking there is no way I would even take a chance....I will ride it with them when they are older and enjoy it at that time, knowing that I took precaution to keep them as safe as possible.
Think about it like this, if the ride has a caution, treat it as if it were medication. Would you take medication that had a caution on it for pregnant mothers? They must have a reason for the caution sign.
All I can say, after having four children, is you do not want to regret it for the rest of your life, always wondering, what if I didn't ride. That would kill you.
Is anything going to happen to your child if you ride, probably not. But, lean on the side of caution, because when that little one is born, and you look into his/her eyes, you will wonder why you even thought about taking this chance.