I worried about this too because my fiance's mother was telling me about how when she was pregnant with him the cord got wrapped around his neck so it is always in the back of my mind. Like the previous comment, try not to look up or think about the bad things. It helps set your mind at ease. Also don't stretch your arms too far above your head or over stretch your stomach too much.
Stay off of google and other such sites like that. I worry a lot and I'm not the pregnant one! Once i stop reading about all the bad things, i felt better and less worried about our pregnancy. I try to focus on the good things and prepare for our new addition to the family. Keep in mind, the things you read about, will help or harm your spirits. Keep good things in mind.