Pregnant and Terrified

My husband and I have been trying for a baby for almost 2 years and we have had 3 miscarriages (the longest I've ever been pregnant was 12weeks).... I just found out I am pregnant again a little over 4 weeks and I am terrified that I will lose this baby too. I don't think I can handle that pain again (physically, mentally or emotionally). Any advice? Has anyone had 3 miscarriages then went on to have a healthy pregnancy? I want to be optimistic and happy but I'm just so scared it will turn out bad again.