Well... Quit reading it?
I know what you mean though. I'm not even a mother, and I already worry incessantly about my kids. Don't even know if i'm pregnant, and I freak out about the same things. I work for an ambulance service, too. So I get to process the paperwork from all of these horrible accidents involving children. But I don't want to turn into one of those severely overprotective parents whose children can't even breathe without permission.
I don't think anything is really
wrong with you. Life is stressful. Add pregnancy to it and it gets even worse. People are inclined to prepare for worst-case scenarios. Just try and find some way to relax and do something to get your mind off it, I guess.
And if you discover a cure for worrying, let me know.