I googled so I can't say I knew it. Hope it's not cheating this is a small snip.
Checkout the bold type. WOW
"Hemorrhages at this time, though often inconsequential, are sometimes extensive; they may produce serious damage to internal organs, especially to the brain, and cause death from shock and exsanguination” (1953, pp. 125-126). Obviously, then, if vitamin K is not produced in sufficient quantities until days five
through seven, it would be wise to postpone any surgery until some time after that. But why did God specify day eight?
On the eighth day, the amount of pro
thrombin present actually is elevated above one-hundred percent of normal—
and is the only day in the male’s life in which this will be the case under normal conditions. If surgery is to be performed, day eight is the perfect day to do it. Vitamin K and pro
thrombin levels are at their peak. The chart below, patterned after one published by S.I. McMillen, M.D., in his book, None of These Diseases, portrays this in graphic form."
Apologetics Press - Biblical Accuracy and Circumcision on the 8th Day