Only 5% of babies come on time so very unlikely she would give birth on your wedding day.
it would probably be a welcome distraction for her, she should bring her hospital bag and notes and her dh should stay sober just incase.
i dont see why you would be hurt anyway, you should be happy for her.
i know you said she is a good friend but on your wedding day you are so distracted by whats going on, you dont really get to chat or appreciate all yoru guests, the day goes do quick. you hardly notice who is there anyway.
this is just what my friends have said - i am yet to marry.
if i was and my friend announced this then i would not be upset about it.
think you're being a little selfish, make sure you dont show your friend this disappointment, that would be upsetting for her.
i assume you are a mother being on here, are you not into kids?
a birth is more important then a wedding!