hi, i asked my doctor a similar question when i was pregnant but it was about riding a push bike and he strongly recommended that i didnt because it puts presure on your pelvis and can cause problems and as meccah24 said it is extremely dangerous
My husband has one and i cant help myself. I love it. It is dangerous regardless. I only went for a quick ride.
You shouldnt risk it,sounds extremely dangerous being preggers on the back of a bike.