I've been doing aerobics my whole life. I'm 27 now and 14 weeks pregnant. I stopped exercising and decided to ride a stationary bike, in moderation of course. I would ride 15 mins, take a break and then ride for another ten minutes. I felt great after two-three months of not doing any exercises and my body was ok with this activity.
However, when I asked my ob/gyn if this was OK, she said NO. I asked her to explain but she just told me NO.

From what I have been reading from different resources, doing some moderate exercise (appropriate for pregnancy) was ok and recommended but she still said NO.

I work 8 hours sedentary kind of work and this activity does me good. I can't walk a lot because I get tired and my feet hurt. I am 12 lbs overweight and I have a vision problem that is not a big deal (-1.25).

Everything else seems to be in order with the baby and me. Do you have any ideas? Should I get a second opinion on the matter?

Thanks