How to Prevent Miscarriage or Complications?

Mom, I'm so scared... this is my third pregnancy. The two previous ones, I miscarried at 16 weeks and 10 weeks. How can we ensure this pregnancy stays healthy? I can't stop blaming myself. My mom and mother-in-law say it's my fault. Now, I'm too scared to do anything, I've completely stopped all activities. I panic at the slightest discomfort... I feel like I'm not going to be a good mom.