The formation of menstruation begins during female puberty, when the ovaries begin to develop and mature and will secrete estrogen and progesterone. Under the effect of estrogen and progesterone secreted by the ovaries, the endometrium will undergo cyclic changes. Higher secretion of estrogen will stimulate the epithelium on the surface of the endometrium, and blood vessels and glands will increase in value, progressing from the value-added phase to the secretory phase. During the secretory phase, the endometrium can reach about 10mm, and then the estrogen in the body will decrease. After the decrease of estrogen, the endometrium loses the support of estrogen, which will easily cause the endometrium to shed. As blood and cervical mucus are discharged from the vagina together, menstruation is formed. Menstruation is regular and comes once a month. Pay attention to menstrual hygiene, do not have intercourse during menstruation, change your underwear regularly, do not be anxious and angry, and do not stay up late to avoid menstrual disorders.