I am a mail carrier & walk 5 miles a day...Dr said that was ok.
I agree with Heather walking is better.
I have been told that you should take it easy, but can still work out. I too jogged before my pregnancy. I now power walk 3-5 times a week for about 25 minutes each time. My doctor says it's good for the baby helps them get more oxygen and of course good for you too. They just want you to keep your heart rate normal. You should be able to talk normally while you are walking. That is why they said walk instead of jog. I am also going to start some prenatal yoga on the days I don't walk :)
Best bet is to ask your own personal Dr.