Menstruation, as the name implies, comes once a month. Its cycle lasts from 21 to 35 days, with an average of 28 days and usually no more than 45 days (except for special quarterly and dark periods). The first menstruation occurs between 13 and 14 years old, and can be as early as 11 years old, but not later than 16 years old, otherwise the appropriate tests should be done. Once the menstruation of each woman is regular, it is generally not easy to change too much, from the feeling of premenstruation, the amount of menstruation, the length of the cycle are more fixed, a slight change will cause women to be alerted. So it is said that a woman no longer knows herself, but must know her own menstruation. Therefore, gynecologists attach great importance to a woman’s description of her menstrual changes and determine whether she is really having a period (although it is not normal) or whether it is not a period at all, but an illusion, an abnormal bleeding. This is where you need to distinguish between “menstruation” and “menses”. If you have the following conditions, it may not be a real menstrual period 1. if the amount of menstruation is significantly reduced or incomplete, or even accompanied by abdominal pain, you should be alert to the occurrence of ectopic pregnancy; 2. if you have vaginal bleeding after sex, especially near your menstrual period, and if you do not have menstrual-like vaginal bleeding in the following days, you should consider cervical lesions; 3. if you have vaginal bleeding after menopause, it may be a symptom of endometrial cancer, cervical cancer or age-related vaginitis. 3. If vaginal bleeding occurs again after menopause, it may be a symptom of endometrial cancer, cervical cancer or age-related vaginitis. In these three cases, you must seek medical attention in time!