Hi Emma, I have also been told that a bigger baby makes for an easier birth. As there isn't as much room in the birth canal to move about so they just pretty much slide out, with a little help of course.
My DD was only 6p8oz when she was born. And she kept on turning and moving around and ended up getting stuck behind some tissue, but in the end I managed to push her through, but she did come out with a cone head