If she bear a maid child, then she shall be unclean two weeks;… and she shall continue in the blood of her purifying threescore and six days. The reason why the duration of the mother's uncleanness is twice as long at a girl's birth as at a boy's, would appear to be that the uncleanness attached to the child as well as to the mother, but as the boy was placed in a state of ceremonial purity at once by the act of circumcision, which took place on the eighth day, he thereupon ceased to be unclean, anti the mother's uncleanness alone remained; whereas in the case of a girl, both mother and child were unclean during the period that the former was "in the blood of her purifying," and therefore that period had to be doubly long. See Luke 2:20, where the right reading is, "When the days of their purification, according to the Law of Moses, were accomplished." For eight days the infant Saviour submitted to legal uncleanness in "fulfilling all righteousness" (Matthew 3:15), and therefore the whole forty days were spoken of as "the days of their purification."
The previous verses having stated the conditions and the term of continuance of the uncleanness arising from childbirth, the three final verses describe the offerings to be made by the woman for her purification. She shall bring a lamb of the first year for a burnt offering, and a young pigeon, or a turtledove, for a sin offering. Two things are noticeable here: first, that the burnt offering, symbolizing self-devotion, is far more costly and important than the sin offering, which had not to be offered for any individual personal sin, but only for human sin, "which had been indirectly manifested in her bodily condition" (Keil); and secondly, that in this one case the sin offering appears to succeed the burnt offering instead of preceding it. No doubt the changed order is owing to the cause just mentioned; the idea of sin, though it may not be altogether put aside (Genesis 3:16), is not to be prominent, as though it were peculiar to the special woman who was purified.