In most cases it is fine to maintain your current exercise level (this includes high impact activities such as running) while pregnant for as long as you are able to AND provided that your doctor doesn't advise you otherwise. However, many pregnant women find this difficult to do due to fatigue, nausea, breathlessness, change in center of gravity etc. as they move through pregnancy. One should never start a new exercise regime while pregnant though.
Exercise should not effect fertility unless you are excessively overdoing it in which case it could prevent ovulation. Since you are ovulating it doesnt sound like this is an issue in your case.
Hi susi! I'm the same as you - I especially love to run. I continued to run not knowing I was pregnant (early), and I also miscarried at 6 wks.
Almost anyone will tell you that if you are already regularly excersising, there is no reason to stop. They say if a baby is going to stay, it is going to stay. I also know people that continued to run halfway through their pregnancy.
After my miscarriage, I put my running on hold to rest for a bit, and long story short, I got my BFP before I even got my next period. I'm not going to start running again now, so I have just been going on brisk walks. I honestly just don't feel comfortably running, as much as people say it should be fine.
I think the most important thing is to listen to your body and don't overdue it. And like the PP says, especially don't start a new routine while pregnant (which I'm sure isn't an issue for you). But I do know that swimming is supposed to be probably the best excersise while pregnant! Good luck, hope you get your BFP soon!