With the use of levonorgestrel tablets, in the case of emergency contraception, breakthrough bleeding may occur 2-3 days after taking the pill, which less often affects the normal menstrual cycle; in the case of establishing an artificial menstrual cycle, menstruation usually resumes 3-7 days after stopping the pill. Levonorgestrel tablets belong to a kind of emergency contraceptive pills, the main ingredient is a large dose of progesterone, mainly used for women’s emergency contraception, but also can be used for the regulation of menstrual cycle. After taking levonorgestrel tablets, women are likely to experience symptoms such as menstrual disorders, mild nausea and vomiting, dizziness and headache, and breast swelling and pain, but they will usually disappear on their own. It is worth noting that not all women are able to take levonorgestrel tablets, such as suffering from a variety of chronic diseases, women who are breastfeeding, and women with a history of mental depression should be careful to take. Therefore, if there is no bleeding similar to the amount of menstruation for more than 10 days after taking the pill, it is necessary to consider the possibility of contraceptive failure. It is necessary to visit the hospital in time to find out the blood and urine HCG status, and if necessary, ultrasound examination should be carried out to find out the condition of the uterine lining as well as the uterine cavity.