A condition called “transfusion-related acute lung injury,” or TRALI, has been linked to plasma from blood donated by women. A few hundred people a year develop TRALI after a plasma transfusion. It is believed to be a result of the recipient’s white blood cells clashing with antibodies which previously pregnant donors produced in reaction to their fetus’ foreign cells. Britain began separating out blood donations by gender three years ago. Only plasma from men was used for transfusions and the TRALI cases dropped. The women’s blood was still used to manufacture blood products such as clotting factors (three quarters of donated plasma goes to the manufacture these products normally, so this was a change in allocation not quantity). American blood banks are now considering separating blood by gender. This news should not discourage any women from giving blood. Your donation will still save lives.