DO IT, DO IT!!
Last night i was a birth partner for my best friend, she wanted a homebirth but due to a shortage of midwives we were setting off for hospital!
as we were leaving she decided she needed the loo....
you know whats coming next.......
her DH "caught" baby while she lent on me for support!
i saw that baby take its first breath!! it was so fab, and thankfully, so calm and simple. everyone was fine and it was utterly brilliant 
and when it was all over i cuddled baby while mum was in the bath and she opened her eyes! i was the first person in the whole world that she saw 
so yes, i have seen my friend in all stages of undress and parts of her anatomy that i never imagined i would! but at the time its simply not an issue and its was so amazing.
Dh's and DP's are good but best friends as birth partners rock! we have now seen each others babies born and it has given us a much closer bond 
im still floating and i thought i would share the happiness 