watching the nature shows where live births are filmed might be a good way to introduce her to the gory stuff. It might be easier to get some doco's from the video store. We had foxtel up until recently and saw a lot of births on there. One recent one was of a giraff giving birth and there was a big explosion of afterbirth with was pretty gross to watch....much worse though was seeing a lion take the newborn.

I think the scariest thing for little kids would be to hear their mum in pain but the good thing about animal births is there isnt much screaming involved.