For a son, or for a daughter; for the birth of a son, or of a daughter; but the purification was for herself, as appears from the following verses. For a sin-offering; either because of her ceremonial uncleanness, which required a ceremonial expiation; or for those particular sins relating to the time and state of child-bearing, of which she is justly presumed to be guilty, which might be many ways.
Related Commentaries of Leviticus 12:6
Leviticus 12:6
6 And when the days of her purifying are fulfilled, for a son, or for a daughter, she shall bring a lamb of the firsta year for a burnt offering, and a young pigeon, or a turtledove, for a sin offering, unto the door of the tabernacle of the congregation, unto the priest: