I am a size 6, but I am not short either (171cms).

TBH, although my birth went well, my son got very stuck, and it took a four hour second stage and a heavily assisted delivery at the end to get him out vaginally! Being a 35 weeker, he was not a big baby, his HC was only 33cms. All the midwives told me he did me a favour coming early, as if he'd gone to FT I probably would have ended up with a c-section. They also said I was lucky to have Ob persist and not take me straight up to theatre! Of course, I may never have that problem again, and don't let me scare you, my birth was a wonderful experience.

I'm not sure I buy into that theory, but there's my experience for you!