The causes of black menstruation include bad lifestyle habits, such as not keeping warm during menstruation, craving for cold, eating cold, spicy and stimulating food, excessive work and life stress, chronic constipation, strenuous exercise during menstruation, uncontrolled sex, excessive dieting and addiction to alcohol and tobacco can all lead to black menstruation.
In addition, genital infections and genital tumours can also cause black menstruation, usually accompanied by fever, abdominal distention and abdominal pain.
Dark menstrual blood after a caesarean section may be related to poor healing of the caesarean incision, where the incision forms a defective depression in the muscular layer where menstrual blood can accumulate and be slowly discharged after menstruation, resulting in a brownish colour of menstrual blood.