Normal menstrual blood is dark red, mixed with small pieces of shed endometrium, vaginal epithelial cells and cervical mucus. In this case, it is important to seek medical attention as soon as possible. 1. Women with anemia. Women with anemia have pink or light red menstrual blood, which is thin and watery, and their periods are usually short, ending in 3 to 4 days. These women usually feel dizzy, have dry and rough skin, and have lower abdominal discomfort and lower back pain during their periods, although they do not have severe menstrual cramps. 2.Attacked by cold. If a woman is attacked by cold, the color of menstrual blood is dark black or red, interspersed with dark red blood clots out. These women will have the feeling of cold in the abdomen during menstruation, and if they have dysmenorrhea, the pain will be aggravated. 3. Poor blood circulation. Women with poor blood circulation usually have a bloated stomach before their periods and constipation during their periods. The color of menstrual blood is dark red and sticky, and sometimes there are dark red blood clots coming out, and there is more blood and longer periods. Because of poor blood circulation, menstrual pain can be so unbearable that you can’t even walk, and you can only rely on painkillers to relieve it. If a woman has this condition for a long time, she may also be suffering from endometriosis or fibroids.