Regular menstruation is a sign of normal ovarian function and the smoothness of the reproductive tract. The amount of menstrual flow is also a sign of normal hormone levels, endometrial thickness, systemic immune function and coagulation mechanisms that reflect ovulation. The frequency of changing sanitary napkins and the degree of penetration are often used to roughly assess the amount of menstrual flow in clinical practice. 1. Judgment of menstrual volume 1. Normal menstrual volume: 20-60ml, need to change sanitary napkins 4-5 times a day, no more than 2 packs of sanitary napkins per cycle (10 pieces per pack); 2. Low menstrual volume: less than 5ml, only a little blood on sanitary napkins, need to change only 1-2 times a day, no more than 1 pack of sanitary napkins per cycle; 3. Excessive menstrual volume: more than 80ml, need to change frequently sanitary napkins, more than 3 packs of sanitary napkins per cycle. 2. Precautions during menstruation 1. Take proper rest, avoid straining, pay attention to warmth and avoid catching cold; 2. Prohibit sexual intercourse during menstruation; 3. Prohibit bathing and vaginal irrigation; 4. Pay attention to vulva cleanliness and wash vulva with warm water every day; 5. Avoid cold and stimulating food in diet.