单项选择题

A.胎儿娩出后24h内阴道流血量大于500ml
B.胎盘娩出后2~4h内阴道流血量大于500ml
C.胎盘娩出后24h内阴道流血量大于500ml
D.胎儿娩出后2~4h内阴道流血量大于500ml
E.胎儿娩出后1周内阴道流血量大于500ml