I'm. 5 months pregnant and have had some spotting; will running hurt my baby? Or cause a miscarriage?

Get checked. When I have a pregnant patient who is a runner, there is usually no problem with her continuing to run during the pregnancy, as long as she is comfortable, and slows down as she gets bigger. However if one of my pregnant patients has spotting, I recommend checking it out and make sure there is no premature labor or weak cervix before exercising again.