I would say A BUNCH! It matters how long you are in labor.. haha. Good question though!
I think it depends on the birth. I assume it would be a lot for any women but i think the actual amount would depend on how long you are in labour for and how long you are pushing. As each birth is different I think the actual amount of calories burned would be different, but we all have more important thing to do while giving birth other then counting calories.
I imagine a great many. This would probably only be a problem if you are malnourished at the time of delivery.
alot cuz u sweat a lot.. well thats what i think..