For experienced joggers, a positive pregnancy test doesn't necessarily mean hanging up the running shoes. "Many women are able to continue jogging while pregnant," says personal trainer Jennifer Johnson, "while others stop because they feel discomfort or pain. Depending on your fitness level, exercise history, medical history and certain pregnancy factors, jogging can be a safe exercise during pregnancy." But if your dream is to go from couch potato to marathoner, hold off for now. Johnson, founder of Fit for Expecting — which offers fitness routines for expecting and new moms — says that pregnancy isn't the time for an inexperienced runner to take up jogging. "If she was interested and physically able [to do] a similar intensity form of exercise, I might recommend options such as hill walking, stairs or water jogging," she says.