Quoting P Pickle Pants:" Putting it all in God's hands would help enormously if I'd never done that before. I have faith in ... [snip!] ... him, but nothing that really put him at risk). I guess its hard to pray for a miracle when I've been let down so many times."
My DH and I were JUST talking about this today. I think that God has the ability to intervene, but it's not something He does for everyone. For what reason, I don't know. I don't have any advice for you, because I will probably be a ball of nerves if I ever get pregnant again, but I really, truly hope things are different this time around.