In general, pregnancy can be detected by a test paper 10 days or more after intercourse. The main principle of pregnancy test paper is to detect the level of human chorionic gonadotropin in urine, which gradually starts to rise after pregnancy, and can usually be detected in women’s urine 10 days after intercourse. Usually, for women with regular menstruation, the test paper can be used to determine whether they are pregnant after 35 days of menopause; for women with irregular menstruation, such as menstrual cycle of 2-3 months or even 6 months, it is usually impossible to infer the time of pregnancy; if the menstruation is delayed compared with the last time and there is intercourse during the period, it is recommended to have a blood HCG test in the gynecology department of the hospital. In addition, early pregnancy test paper is prone to false positive or false negative results, which can only be used as a preliminary screening, and blood HCG and ultrasound tests are still needed to confirm the diagnosis if necessary.