FDA guidelines allow volunteer whole blood donations every 56 days, plateletpheresis donations twice a week up to 24 times a year, plasmapheresis twice a week (as long as total protein and immunoglobulin levels remain adequate) and double red cell collection by apheresis every 112 days.
Every 6 months.
three to four times....
Around 13.6 million people in the United States alone donate blood each year. This number can vary depending on global health crises, natural disasters, and other factors that may increase demand for blood donations.
2 times in a year
250
3
Once.
Once a year.
twice
Normally once.
2
anytime it wants
Small mammals like mice and shrews can give birth many times in a year.