WHAT DO GUYS THINK? should i worry?

i am pregnant and this is my first pregnancy so i am scare of alot things and for some reasons i think negative i heard that i the reason why i think like that is because i've never been pregnant before well anyway some lady told me because i always think oh what if my baby comes out sick or something i don't know why(lately i haven't tought of that)but that lady said if i think like that it will come true because im just thinking about that is that true? how many of you tought like that?and how did you get over it?