Amenorrhea is divided into primary amenorrhea and secondary amenorrhea. Primary amenorrhea is caused by congenital or hereditary factors and has no precursor symptoms, while the precursor symptoms of secondary amenorrhea are related to the causes of amenorrhea, which need to be analyzed specifically for the causes. 1. Hypothalamic amenorrhea: amenorrhea is caused by lesions of the central nervous system and the hypothalamus. Before amenorrhea, there may be symptoms such as weight loss, anorexia, nervousness, anxiety and low blood pressure. 2. Pituitary amenorrhea: caused by organic lesions or dysfunction of the pituitary gland, patients may have symptoms such as obesity, hirsutism, acromegaly, hypertension, rough skin, excessive red blood cells and so on. 3. Ovarian amenorrhea: amenorrhea due to the decrease of estrogen secreted by the ovaries, there may be precursor symptoms such as vaginal dryness, loss of libido, pain during sexual intercourse and irritability. 4. Uterine amenorrhea: amenorrhea due to uterine adhesions caused by infection, trauma, etc. It usually occurs after abortion and scraping, uterine surgery, cervical conization surgery and other surgeries. 5. Others: endocrine disorders can also lead to amenorrhea, such as thyroid and adrenal gland dysfunction, which may cause aura symptoms such as fatigue, anorexia, low blood pressure, and chills. When menstruation is delayed and accompanied by the above symptoms, you should consult a doctor in time to clarify whether it is amenorrhea, and treat the cause in time.