A delayed menstrual cycle is not a sure sign of pregnancy because, in addition to the possibility of pregnancy, a delayed menstrual cycle can also be caused by endocrine disorders. The menstrual cycle is controlled by the hypothalamus-pituitary-ovarian axis. Problems in any one of the three areas of the hypothalamus, pituitary and ovaries, such as a change in the living environment, mental stimulation, staying up late all the time, a sudden drop in body weight in the near future, or space-occupying lesions on the ovaries, can lead to endocrine disorders in a woman, resulting in abnormalities in her menstrual cycle. If the menstrual cycle is usually regular and there is no contraception, delayed menstruation should be considered as a possibility of pregnancy, and a pregnancy test should be conducted to confirm whether the woman is pregnant or not. If pregnancy is ruled out, the delayed menstruation should be considered whether it is caused by the stimulation of adverse factors or ovarian factors, and further investigation is needed to find out the cause of the disease.