Leviticus 12:1-8 describes the purification system for women who give birth in ancient Israel. This is a part of the ritual purity laws and offers instructions on how a new mother is to be purified of niddah (womb bleeding) uncleanness after childbirth. One puzzling aspect of childbirth purification is why the mother must wait only 40 days after giving birth to a boy, but 80 days for a girl? Additionally, she must offer a burnt and sin offering, even though this is typically reserved for individuals who have recently been healed of a bodily discharge disorder caused by sin (Lev 15:13-15; 28-30). Having a child isn’t a sin or a disorder, so why?
Science suggests that a woman’s womb takes around 6 weeks (42 days) to heal. If a woman gives birth to a son, the mother is unclean for seven days, just like during menstruation. Then she must wait for her womb to heal (be purified) from bleeding for 33 days, making a total of 40 days. It’s two weeks and 66 days (80 days) for a baby girl. One theory is that purification for girls is twice as long because it represents the fact that there are two womb carriers (or two females). Another theory is that it was related to the circumcision of males. Maybe somehow the male is purified by the circumcision, so the timeframe is longer for girls. However, this would mean all uncircumcised boys would require 80 days, and I don’t see any reference to that in the text. The other option is that since a baby girl has a womb, and while it may not be bleeding, this extra time for purification represents her ability to give birth in the future. I lean towards the second one since it seems more consistent. Below is a resource that provides a more in-depth explanation of Leviticus chapters 12-15.
When the 40 or 80 days are over, the mother brings two offerings (sin and burnt offering) to the Tabernacle. Childbirth isn’t a sin, but we are all born with a sinful nature. It seems more likely that the sin offering covers the sin nature of the child rather than any sin of the mother. The rabbis believed at that time that a person can be guilty of and even punished for sin from the womb. That is why the disciples asked Jesus if the blind man who was born blind was born blind because of sins he committed before he was born or his parents’ sins in John chapter 9. Some people will take this verse out of context to suggest that Jews in the 1st century believed in Reincarnation, but that is not the case; they were talking about sin in the womb—more on Reincarnation in the Bible here.
This is why Jesus refers to salvation as being born again (John 3:1-15). We are all born in water in our natural birth, but the rebirth in the Holy Spirit (John 3:5-7), which is connected to the blood sacrifice of the messiah (Jesus), makes us born again when we believe in him. In Luke 2:21-24, the baby Jesus is circumcised eight days after his birth. Then, 40 days after his birth, Mary and Joseph offer a purification offering, as mandated by the law of Moses in Leviticus 12. This shows that Jesus’ parents helped Jesus fulfill the law even as a child.
Resources:
In-depth teaching by Jim Staley on this subject