Oh girls! How do you deal with fears?

Oh girls! How do you deal with fears? I'm 30. Waiting for the third one. I gave birth to the first two without any worries, I had a son at 22 and a daughter at 19. Now I worry about everything! Is everything okay with the baby? What if something happens during delivery? Maybe it's better to have a cesarean section? (Just my kids are big: my daughter was 4300, my son - 4900). What if it's a big one so I don't crush him... What if? And what if...? And I understand that I need to think good things, but still... Maybe it's age?