1. Definition and cycle of menstruation Menstruation is the cyclic discharge of blood from female reproductive organs, marking the beginning and end of female fertility. The menstrual cycle generally lasts 21-35 days and lasts 3-7 days. 2. Precautions during menstruation During menstruation, women need to pay attention to hygiene and avoid infection. At the same time, bad habits such as excessive exercise and improper diet should be avoided. three,