If you have delayed menstruation for eleven days and still can’t detect pregnancy, it may be due to the normal physiological cycle, or it may be due to factors such as menstrual disorders or polycystic ovary syndrome. 1. Normal physiological cycle: Some women have a long physiological cycle and may experience delayed menstruation. 2. Menstrual disorders: endocrine disorders due to long-term mental depression, stress or taking contraceptive pills and other factors, resulting in abnormal menstruation, which then shows the phenomenon of delayed menstruation for eleven days or still can not be measured. 3. Polycystic ovary syndrome: It is the most common endocrine metabolic disease in women of childbearing age, characterized by clinical or biochemical manifestations of hyperandrogenism, persistent anovulation, and polycystic changes in the ovaries, which can lead to menstrual abnormalities, such as a prolonged menstrual cycle or even amenorrhea. There may be other reasons for delaying menstruation for eleven days or not being able to detect pregnancy, so it is recommended to consult a doctor in a timely manner, complete the relevant examinations, and clarify the cause of the disease under the guidance of a professional doctor for targeted treatment.