Probably because of the risk of falling off the bike. Injuring yourself or the baby. Exercise is great! Highly recommended too. But just use good judgement about the activities you partake in and rather or not they could be potentially harmful to you or the baby.
Good luck and be safe..
Good luck ladies. Wish I had a bike x
I started riding a regular bike at 20weeks, now im 29 my doc said it was fine and I haven't gotten hurt or fallen..just be careful
If you want ride a bike, you can do a stationary one. Like jelarin said your center of gravity changes and you don't want to fall off your bike.
I ride my bike and do fine. I'm only 13 weeks thigh. When you start showing more, and your center of gravity changes, you might want to be careful, but just do moderate exercise, and don't push yourself and you should be fine. Anything low impact.
If you were active before you were pregnant you can remain active until it is uncomfortable. For example, if you play tennis the time a week it is OK to keep playing tennis just don't push yourself as hard. If you went to the gym daily it's OK to keep going to the gym just don't push yourself as much. I suggest you stay away from weight lifting but any kind of cardio is on in moderation. It's just not good to start a new workout routine while pregnant. Swimming is something great to do while pregnant.