If you ran regularly before getting pregnant, and have a “healthy pregnancy” experts now say it's fine to continue, just ask your doctor. But frankly, any woman facing infertility knows intuitively that it makes sense to lie low and rest until you get a confirmed heartbeat and strong pregnancy ultrasound at 8 weeks. Switch to brisk walking, hiking, or walking hill intervals on the treadmill. Also don’t begin a running routine when trying to get pregnant if you’ve never really done it before. If you feel safe working out remember the first trimester is when the baby's major organs are forming, and overheating is dangerous so go easy.
Source: BabyCenter
Source: BabyCenter