I was told not to after 12 weeks by my Dr for the chance of falling since we have less center of balance
I'm 29 weeks and ride bike all the time. I was told it was safe as well and I enjoy it!
It is fine when you are not far along I would say but I wouldn't try riding while 8 months pregnant!
Yupp! It's classified as a safe excercise during pregnancy (: along with walking and swimming! (: