Calculate the number 537

I mowed the lawn today, and after doing so I sat down and had a cold beer. The day was really quite beautiful, and the drink facilitated some deep thinking on various topics.
Finally I thought about an age old question:

Is giving birth more painful than getting kicked in the nuts?
Women always maintain that giving birth is way more painful than a guy getting kicked in the nuts.
Well, after another beer, and some heavy deductive thinking, I have come up with the answer to that question.
Getting kicked in the nuts is more painful than having a baby; and here is the reason for my conclusion.
A year or so after giving birth, a woman will often say, "It might be nice to have another child."
On the other hand, you never hear a guy say, "You know, I think I would like another kick in the nuts."
I rest my case.
Time for another beer.