If there is no pregnancy, delayed menstruation may be caused by the following reasons: First, premature ovarian failure, which causes the hormone level in the body to drop, and it will lead to the absence of menstruation. Second, due to endocrine disorders, such as long-term work stress, poor sleep or anxiety, it will lead to delayed menstruation. Thirdly, delayed menstruation can also be caused by certain diseases, such as polycystic ovary syndrome, hyperprolactinemia and hyperandrogenemia. Thinning of the uterine lining due to oral contraceptive pills, which eventually leads to lack of menstruation, is also a major cause. Therefore, if you are not pregnant and do not have menstruation, you have to give treatment according to the cause of the disease, and menstruation will be restored clinically.