My wife biked well into her 7th month, in urban traffic. She stopped due to balance issues and it became more difficult for her to carry the bike up 3 floors to her office.

She always enjoyed the shocked look on the faces of other women when she walked into her doctor's office with her riding clothes, shoes and helmet.

Her doctor gave her the usual warnings, but also said the benefit of staying in shape should not be overlooked, especially as my wife was going for a vaginal birth after having a cesarean with our first.