Circumcision is the removing of the male foreskin and as a consequence, it is a rather bloody process. Therefore, here we provide scientific evidence for why circumcision has to be on the eighth day.
4 thousand years ago, Yahweh instructed Abraham to circumcise males on the eighth day:
This is My covenant, which you shall keep, between Me and you and your descendants after you: every male among you shall be circumcised. And you shall be circumcised in the flesh of your foreskin, and it shall be the sign of the covenant between Me and you. And every male among you who is eight days old shall be circumcised throughout your generations, a servant who is born in the house or who is bought with money from any foreigner, who is not of your descendants. (Genesis 17:10-12 NASB)
Abraham followed this prescription with his son Isaac:
Then Abraham circumcised his son Isaac when he was eight days old, as God had commanded him. (Genesis 21:4 NASB; cf. Acts 7:8)
Some 600 years later Yahweh gave Moses the same instruction for the Israelites:
On the eighth day the flesh of his foreskin shall be circumcised. (Leviticus 12:3 NASB)
Why did Yahweh order circumcision on the 8th day for Abraham’s male descendants? Why not sooner or later? Why did it need to be on Day Eight?
In the 1930s, Danish researcher Henrik Dam and American researcher Edward Doisy found that which was required for blood to clot. They shared the 1943 Nobel Prize in Medicine for this research.
The human body has 2 blood clotting elements. One of them is called Vitamin K. Vitamin K is not formed in the body up until the 5th to the 7th day.
The 2nd clotting factor which is essential is called Prothrombin. It surprisingly enough develops to 30% of normal by the 3rd day of life and after that with seeming in-consequence, peaks at 110% on the 8th day, just before leveling off at 100% of normal.
If vitamin K is not present when a baby boy is circumcised, the baby will bleed to death. The reason why Yahweh established Day Eight for circumcision is that vitamin K peaks in a newborn at 8 days of age. The 8th day is the optimum day for circumcision because of the highest presence of the clotting factor vitamin K.
Today when baby boys are circumcised within a couple of days of birth, they are administered vitamin K to help with blood clotting.
How did Abraham and Moses know to circumcise on the 8th day? Solely the Creator, who understands every intricate detail of human physiology (since He made it), could have disclosed this to them.