How to comfort your girlfriend through labor ?

Mostly be there. Fetch things for her and stay positive. Don't compare the pain to that of getting kicked in the nuts.

I definitely would not say "It's okay babe, I know how you Feel"! Not unless you want your scrotum as a new hat post three seconds flat after saying it!

Just be there for her.
But be there to satisfy HER needs, not yours.

First ask her if she wants you there beside her.

Have some popcicles,ice chips and water ready and be prepared to remain caring and supportive while being yelled at.Enjoy one the most amazing experiences of your life.

No girlfriend so I have no fucking clue about this.

Hold her hand and employ the Lamaze technique (?)

Just keep repeating "It could be worse"

good luck