The Law specified that a woman who gave birth to a son would be ceremonially unclean for 7 days, while a woman who gave birth to a daughter would be unclean for 14 days. The best understanding to account for this difference is found in the Jewish perspective regarding holiness. First, ritual purity is of great importance in the Jewish tradition. A woman traditionally remained impure for seven days following her monthly menstruation cycle. Impurity in this context is not intended to imply sinfulness or inferiority; rather, it emphasizes the importance of holiness within a woman’s body and the power to create a new life through union with her husband.
At childbirth, this same tradition continues to operate. In Leviticus 12, if a woman has a son, she is unclean for 7 days and her son is circumcised on the eighth day, following God’s covenant with Abraham. The woman must then wait 33 days to be purified from her bleeding for a total of 40 days.
“And the Lord spake unto Moses, saying, Speak unto the children of Israel, saying, If a woman have conceived seed, and born a man child: then she shall be unclean seven days; according to the days of the separation for her infirmity shall she be unclean. And in the eighth day the flesh of his foreskin shall be circumcised. And she shall then continue in the blood of her purifying three and thirty days; she shall touch no hallowed thing, nor come into the sanctuary, until the days of her purifying be fulfilled. But if she bear a maid child, then she shall be unclean two weeks, as in her separation: and she shall continue in the blood of her purifying threescore and six days.” Leviticus 12:1-5
When a woman gives birth to a daughter, two differences are noted. First, instead of being unclean for 7 days, she is unclean for 14 days, or twice as long. Second, instead of waiting 33 days until being purified, she must wait 66 days, again twice as long, for a total of 80 days (Leviticus 12:5). According to Jewish tradition, this period is twice as long to account for the purity of both the mother and the daughter. Therefore, the time period is twice as long as when a mother gives birth to a son.
Physically, there is no reason a woman should be unclean for longer or require longer to recover after giving birth to a daughter. Tradition suggest that more time was given for a mother to bond with a daughter and to provide protection for her, but this is not found in scripture.
There is also a tradition that the period of cleansing was shorter after the birth of a boy out of hope that the boy would be the Messiah. While this is an interesting theory, the hope that a male child would be the Messiah is nowhere mentioned or even hinted at in Leviticus chapter 12.
The most likely explanation is that the different lengths of time a mother was considered “unclean” involve something spiritual, to remind Israel of Eve’s sin. We know that men and women were both created in the image of God (Genesis 1:26–27), but sin affected the role of each (Genesis 3:16; 1 Timothy 2:11–15). It is the Lord alone who fulfilled the Law and takes away the curse, making the practice unnecessary (Matthew 5:17; Galatians 3:13).