 But only about 3% of the population donates. Without more donors, hospitals may not have the blood needed to save lives. That's why the American Red Cross needs people to help restore the A's, B's, and O's that are depleting each day. When you make your appointment to donate blood at redcrossblood.org forward slash missing types, you can help give strength to kids, parents, and grandparents who face life and death challenges.