A little scared. Sorry this is long. Any input is really appreciated!

This is my 3rd pregnancy. My 1st was full term with no problems. Had a very healthy boy. My 2nd pregnancy I found out I was pregnant at 6wks then had a miscarriage at exactly 8wks. Now I am 4wks pregnant and I was wondering if since I had a previous miscarriage am I more likely to have a miscarriage this time, Should I be worried? I was thinking that my miscarriage was caused by me because before I found out I was pregnant I was laying in tanning beds and smoking. I am trying not to worry/stress. I haven't laid in tanning beds in months and I don't smoke anymore!