“…Previous findings on blood group differences in donation rates are somewhat mixed. Though some studies found no association between blood groups and donation rates, indicating that blood donation is driven by various motivations (Wevers, Wigboldus, De Kort, Van Baaren, & Veldhuizen, 2014;Wildman & Hollingsworth, 2009), others found O-donors to have a higher chance of ever donating (Sasaki, Funasaki, Kurokawa, & Ohtake, 2020), O-negative donors to have a higher chance of returning for a subsequent donation (Gemelli, Hayman, & Waller, 2017), and being a high-frequency donor (Veldhuizen, Doggen, Atsma, & De Kort, 2009). More specifically, Sasaki and colleagues (2020) found that the positive association between O-blood group and blood donations was especially present when donors knew that their blood could be used to treat all patients in need of blood.…”