Does insufficient qi and blood lead to less menstrual flow?

Insufficient qi and blood is likely to cause less menstruation, is a common cause of less menstruation. But on the other hand, less menstruation must be caused by insufficient qi and blood, so there is a connection between the two, but the reverse can not be, can not attribute less menstruation to insufficient qi and blood. At the same time, it should be noted that insufficient qi and blood will not only cause less menstruation, but also may cause excessive menstruation or dripping.