Normal menstruation lasts 28-30 days, and if it is delayed for 15 days, it is considered abnormal. There are many reasons for delayed menstruation: i. Stress. Women of childbearing age who are under prolonged stress will inhibit the pituitary function of the ovaries so that the ovaries do not ovulate and menstruation will be delayed. Similarly prolonged depression, sulking or poor mood can also affect menstruation. Second, cold during menstruation will make the blood vessels in the pelvis contract, leading to ovarian dysfunction, causing delayed menstruation, or even amenorrhea. Third, greedy for cold. From the perspective of Chinese medicine analysis, qi and blood deficiency, kidney deficiency and qi stagnation and blood stasis, such as emotional fluctuations, environmental changes, overwork, excessive dieting, irregular life and work, especially during or before the period of over-eating cold or cold stimulation, will make the pelvic blood vessel contraction, resulting in delayed menstruation, or even the color of the color of the black, or even amenorrhea. Fourth, electromagnetic wave. Various household appliances and electronic equipment in the process of using, will produce electromagnetic waves. Electromagnetic waves acting on the human body for a long time will have an impact on women’s endocrine and reproductive functions, leading to endocrine disorders, menstrual disorders and delayed menstruation. Fifth, the abuse of drugs. Abuse or frequent use of antibiotics in large quantities, reduce the body’s own resistance, resulting in body dysfunction, causing delayed menstruation, non-ovulation, or even amenorrhea. Smoking. Nicotine in tobacco can reduce the secretion of sex hormones, interfere with the physiological process of menstruation, causing menstrual disorders and delayed menstruation.