Oh no! that's one of those fears that ppl will have and you can't really help calm down. Just try to show her as much research as possible showing how rare that is and usually it's because of a preexisting issue. It probably won't help but it can't hurt either. :( I've dealt with anxiety my whole life so I know how it feels to have those completely irrational fears. it really sucks! I definitely feel for her.

The hospital staff will do anything and everything to make the delivery safe for her and the baby. If they see any complications arise, they'll act accordingly to save both. That fear is a scary one to have, but it's less common nowadays unless something horrible occurs :) Just tell her not to worry, and I agree with the above comment ^

oh no, that is terrible. just try to be supportive for her, don't dismiss her fears. that will probably go further than anything.