Menstruation can be affected by environment, mood, disease and medication. Delayed menstruation in the absence of pregnancy is related to emotions, such as being under stress, tension and anxiety, which can cause menstrual disorders and affect menstruation, and diseases can also cause delayed menstruation, such as premature ovarian failure, cervical adhesion and polycystic ovary syndrome. Long-term use of a large number of hormonal drugs can also affect the onset of menstruation, such as emergency contraceptives, weight loss drugs, and cold in the uterus can also cause delayed menstruation, the cold in the uterus will affect the growth of the endometrium, can not reach the thickness will affect the menstruation, when the delayed menstruation can be injected progesterone or progesterone drugs, the menstruation will come. To avoid diseases, it is better to have an ultrasound and gynecological examination.