If you have a history of intercourse, it is recommended that you first rule out pregnancy by buying urine pregnancy test strips and taking morning urine to find out the answer. Secondly, if you are not pregnant, you need to rule out endocrine causes. In addition to the hypothalamic-pituitary-ovarian axis, menstruation is also affected by external factors such as changes in weather, emotional changes, changes in nutritional status after heavy physical activity, etc., which can affect normal menstruation. Thirdly, cervical or vaginal diseases should be ruled out and regular screening for cervical cancer should be performed, and dual screening with TCT and HPV is recommended over the age of 30.