Why did my hiv risk rise after blood transfusion for postpartum hemorrhage?

Massive transfusion.: You were probably transfused with a lot of blood without the time to properly crossmatch it. Although blood units that are donated are typed, screened, and checked for infection, not all infections are always readily apparent. Since this was an emergency and a lot of units might have been given, infection risk goes up, especially if units were not crossmatched yet.