Matthew Poole and continuators on Leviticus 12:5

5 But if she bear a maid-child, then she shall be unclean two weeks, as in her separation: and she shall continue in the blood of her purifying threescore and six dayes .

The time in both particulars is double to the former, not so much from natural causes, because the purifications in female births are longer and flower, which if it were true, yet doth not extend to any such time as here is mentioned, as for moral reasons; either to be as a blot upon that sex for being the first in mans transgression, 1 Tim. 2. 14. or to put an honour upon the Sacrament of Circumcision, which being administred to the Males did put an end to that pollution sooner than otherwise had been: or to shew the priviledge of the man above the woman, and that the women were to be purified sanctified and saved by one of the other sex, even by the man Christ Jesus without whom they should have still continued in their impurity.