Menstruation delayed eight days and not pregnant may be a normal situation, but also may be caused by misdiagnosis, polycystic ovary syndrome, pituitary tumors and other diseases, the patient should consult a doctor in a timely manner to clarify the cause of the cause of treatment. 1. Physiological conditions: Normal people may experience delayed menstruation or even amenorrhea when they are nervous, under work pressure, or have excessive weight loss. Such people should pay attention to relaxing their moods and adjusting their lifestyles, and generally do not need special treatment. 2. Misdiagnosis: If a woman who has sex with a delayed menstrual period for eight days is not pregnant is tested with a test strip, there may be false negatives, and she should go to the hospital in time to complete the relevant examinations. 3. Polycystic ovary syndrome: a common endocrine metabolic disease in women of childbearing age, the patient will have delayed menstruation, low menstrual flow, hirsutism, acne and other symptoms, this group of people have fertility requirements can be ovulation therapy. 4. Pituitary tumors: a group of tumors originated from adenopituitary gland and neuropituitary gland, patients will have symptoms such as irregular menstruation, urolithiasis, vision loss, etc. They can be treated with medicines such as bromocriptine and octreotide under the guidance of doctors, and surgery can be carried out if necessary. Women of childbearing age can be temporarily observed if the menstrual period is delayed for 8 days, and if it persists without menstruation, they need to consult a doctor.