The Baby Boy Payoff:

More evidence that men are squealing little chauvinist piggies: It seems daddies not only shower their sons with more attention but also work harder and earn more money after the birth of a boy than they do after the birth of a girl.

At the same time, the sex of a child has no impact on the hours that women work outside the home or the wages they earn, reported economists Shelly Lundberg and Elaina Rose of the University of Washington. Washington Post