Normally, a person looses around 40ml of blood per period with people having 450 periods on average in their life. This means that on average a person would loose 18l of blood from menstruation alone. With the average human having between 4.5l and 5.7l, you'd only need to sacrifice 4 people to the menstruation gods to never have to shed blood for that ever again. ~~In my experience, it works best when sacrificing transphobes or terfs.~~
As a quick side note: I hate it when someone refers to it as a "pseudo-period". The hormonal cycle is very very real, I can assure you that.
Do you have a sauce in thede numbers?
amount of blood per period: https://www.menstrual-matters.com/bloodloss/ (35 - 40ml, i took the higher estimate, sources for the values at the bottom)
amount of periods in total: https://pmc.ncbi.nlm.nih.gov/articles/PMC2244694/ (451.3, rounded down to 450)
40ml * 450 = 18000ml = 18l
I can't find the original numbers for average blood content in a human but the general consensus seems to be that it's between 4.5 and 5.5. It doesn't really matter though since, even if we say that you'd sacrifice 4 people with only 4.5l of blood, you'd still reach your desired 18l of sacrificial blood.
thx