As long as you keep your heart rate below a certain point, running should be fine- especially if you had been running regularly before your got pregnant. My doctor said that I could exercise just as I did before, I would just have to take it easy and not let my heart rate get above 140. With the additional blood your body is taking on, this happens easily. So, your running may have to turn into jogging! And as you move further into your pregnancy, maybe even speed walking.
Exercise regularly, steadily, and don't push it!
Good, reputable article:
Webmd.com, my doctor, Mayo Clinic Guide to a Healthy Pregnancy, 8 mos. of a fit pregnancy, wife of a distance runner
· 1 decade ago