Upset and worried

I've been having indigestion here lately. I'm 20 weeks. This is my first pregnancy and I heard two girls die with the umbilical cord came out before their actually labor. My mom keeps telling me they had complications risk with their pregnancy and I don't. I just went to my check up two weeks ago and everything was fine just my placenta is sitting on top of my uterus but the doctor didn't seem to be worry. All I want to do is cry!!!