Women don't sense pain in the same way men do
arstechnica.com
arstechnica.com
Tomorrow on cnn.com: "Scientists say women don't feel pain"
The difference I see is men didn't need to be able to tolerate and survive that pain, 'cause they were dead anyway. Women, on the other hand, really need to be able to survive and cope with the pain of childbirth so they can raise their child.
In addition I'm pretty sure I read that on average females have a lower pain tolerance then men. Though it can be changed by training... relatively easily too.