Leviticus 12:5

“But if she bear a maid child, etc.] A daughter, whether born alive or dead, if she goes with it her full time: then she shall be unclean two weeks; or fourteen days running; and on the fifteenth day be free or loosed, as the Targum of Jonathan, just as long again as for a man child: as in her separation; on account of her monthly courses; the sense is, that she should be fourteen days, to all intents and purposes, as unclean as when these are upon her: and she shall continue in the blood of her purifying sixty and six days; which being added to the fourteen make eighty days, just as many more as in the case of a male child; the reason of which, as given by some Jewish writers, is, because of…”

“Some have thought that this doubling of each of the two periods was intended to remind the people of the fact that woman represents the lower side of human nature, and was the first to fall into temptation. 1 Timothy 2:13-15; 1 Peter 3:7. The ancients had a notion that the mother suffers for a longer time after the birth of a girl than after the birth of a boy. The period required for the restoration of her health in the one case was thirty days, and in the other, it was 40 or 42 days. This notion may have been connected with a general custom of observing the distinction as early as the time of Moses. return to 'Top of Page'”

“Threescore and six days - The time in both particulars is double to the former, not so much from natural causes, as to put an honour upon the sacrament of circumcision, which being administered to the males, did put an end to that pollution sooner than otherwise had been. Leviticus 12:6”

“12:5 two weeks . . . sixty-six days: The total is eighty days, double the time required for the birth of a son (see also 27:2-7).”

“Lev 12:2, Lev 12:4; Gen 3:13; Ti1 2:14, Ti1 2:15 Leviticus 12:6”

“But if she had given birth to a girl, she was to be unclean two weeks (14 days), as in her menstruation, and then after that to remain at home 66 days. The distinction between the seven (or fourteen) days of the "separation for her infirmity," and the thirty-three (or sixty-six) days of the "blood of her purifying," had a natural ground in the bodily secretions connected with child-birth, which are stronger and have more blood in them in the first week (lochia rubra) than the more watery discharge of the lochia alba, which may last as much as five weeks, so that the normal state may not be restored till about six weeks after the birth of the child. The prolongation of the period, in…”