what is a dangerous temp during pregnancy?

I am taking regular Tylenol to keep my fever down and help with the headache, but I'm only taking it like every 8-9 hrs. I am worried about taking it too much, but also concerned about a fever. Right now it's at 100.4. I know that's not terrible, but what is too high during pregnancy. I have never been sick during any of my pregnancies and we have a terrible history from trying. Things are going great so far and now I'm stressing over this. Any advice and/reassurance is greatly appreciated. Thank you in advance.