Sure its safe. If your body gets over fatigued then slow down cause that might cause problems: signs of over fatigue: insomnoa, having to shorten a work out because your body just cant go any further. -feeling like this at the end of a good 30-60 mion workout is normal, feeling like this 10 min into a workout means your body needs a rest day. Keep well hydrated before and after run. Stretch before and after. Dont stop once you become pregant.