Provided by CLAL: The National Jewish Center for Learning and Leadership, a multi-denominational think tank and resource center.
The beginning of Parashat Tazria describes the law regarding a woman after childbirth. She first goes through a period of ritual impurity, then through a period called "blood purification." Both of these time spans are twice as long after bearing a daughter as after bearing a son. This discrepancy is profoundly disturbing. Even more troubling is the requirement that, after her purification period, the woman bring a burnt offering and a sin offering to the Temple.
Why a sin offering? Isn’t childbirth a mitzvah (commandment)? How has the woman sinned?
Perhaps the Torah anticipates that when a woman gives birth she may well be overwhelmed by her accomplishment. She feels so proud of what she has done that she takes full credit for the glory of new life! In so doing, she ignores the major role played in the miracle of reproduction by God, whose hand is seen in all such "natural" wonders. Her lack of humility and failure to acknowledge God’s role are her sin.
Then why doubled periods of impurity and purification for a daughter? One possibility is that giving birth to a virtual copy of herself, a girl who will someday also be able to create life, increases a mother’s pride and so requires a longer punitive period.
Another is that the period of impurity after bearing a son is interrupted by the brit milah, circumcision (Leviticus 12:3). This powerful ritual reminds the proud mother of God’s role in the birth and in the continued life of her son. Since ancient Judaism had no covenant ceremony for daughters, a longer impurity/purification period was required.
Modernity has taught us to recognize the absolute covenantal value of Jewish women, and the resultant development of covenant rituals for newborn daughters enables them, like their brothers, to remind us of God’s presence in the world.