Wow, thanks for this thread, Dollyroux, and thanks for that info, Trillian! Everyone thought I was nuts for holding myself up off the bed (the midwives wouldn't let me birth on all fours/squatting/any position that would allow the birth canal to be fully open as 'it's interfering with the monitoring equipment, just lay back') with my arms so that my bum was completely off the bed and DD could get out...
My arms were dead for days afterwards because of the strain, but it felt better than trying to force her through a semi-closed canal!