Kezty, I really recommend the movie Orgasmic Birth - you can find clips of it on youtube. I know the name is a little confronting, but it's more about the emotional state a woman is in during birth rather than an actual orgasm... I watched it while pregnant and it really helped me prepare.
BreadRoll, your DW might like to have a look too She needs to do whatever she feels is best for her and bub, but natural birth isn't an emergency. It doesn't have to be painful. It can be totally blissful and the best high you've ever had in your life! During my DS's birth I kept saying to myself "This can't be it. This isn't hard enough. It's going to get worse and I won't be able to do it" Next thing I knew I was pushing, and there he was.