Matthew Poole and continuators on Leviticus 12:6

6 And when the dayes of his purifying are fulfilled, for a son, or for a daughter , she shall bring a lamb of the first year for a burnt-offering, and a young pigeon, or a turtle-dove for a sin-offering , unto the door of the tabernacle of the congregation unto the Priest:

For the birth of a son, or of a daughter: but the purification was for her self, as appears from the following verses.

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.

Marginal references: Heb. son of his year.