Leviticus 12:5 refers to how if the woman gives birth to a baby girl, then the mother will be unclean for two weeks. She will also go through a 66 day purification of her blood. This is twice as longer for giving birth to a female than a male! By the Lord stating here about the woman having a customary impurity, the days of her being unclean are different respectively for either sex of her newborn. This leads me to believe this customary impurity only occurs whenever she gives birth.
The way I am just feeling right now is that the person isn't at fault for being born a female. I think this whole impurity could be some type of spiritual thing. Maybe, the mother has some type of bond that the Lord recognizes. From the last couple verses, with the male baby being circumcised, that is what probably cuts the purification time shorter. It's done on the eighth day which would be the end of the mother's impurity. I have heard attempts of that nature being done with females, but it's dangerous and in humane to the point those babies can die! The male organ still gets full functionality so it's different.
Honestly, the New Testament says that men and women are equal with being children of God. A verse says that heaven will not have something like male or female, so no one would be giving birth in the afterlife! No more suffering and no more tears and something unimaginably good. This guy I know says that he would be all about his sons and try to put his daughters up for adoption. It's funny, but I think he's a creep and undeserving of becoming a father.