With my first I wasn't worried/scared a bit. My antenatal classes didn't mention anything to do with labour and nobody wanted to share their birth experiences with me so I really didn't have a clue what to expect!
My friends dad asked me if I was scared and I said no, he called me a liar because everyone gets scared 
This time around I feel exactly the same, only I know what to expect and it still doesn't bother me.
Oh asked if I was scared and I said no, he said 'not even a little?' no.. its not a feeling I choose to switch off I'm just not worried, end of.
In fact, I have my dd name tattooed on me and I'm more worried about having my sons name tattooed on me because I had such a traumatic experience with my last!
I get this reaction a lot when I tell people the truth, I feel as though I should lie instead and say yes I'm bloody terrified just to satisfy them!