Jenn, unlike the first responder to your post, I think this is a very relevant question for a public forum. The overwhelming risk with cycling in pregnancy is trauma. You should be fine bicycling until about 20 weeks of gestation. In the last trimester, I would caution you to be very careful or to stop cycling due to enhanced risk of fall with possible adverse outcome for the fetus. For any fall beyond 24 weeks, your doctor will probably advise electronic fetal monitoring.

And I hope that some of the other ladies will share their experiences as well as some of the advice they have received.