Depends on the source. WHO says >= 500mL and American College of Obstetricians and Gynecologists says >= 1000mL.
The table in the Extra field says 500mL after vaginal delivery; if it is contested, then the card can be separated by "according to WHO … " “according to ACOG …”
Didnt check the extra field. The table looke old so I checked UW again and the table and definition seem to be the same.