Generally, early pregnancy test strips can be used to detect pregnancy about a week after intercourse by testing the morning urine. The longer the time after intercourse, the higher the accuracy rate, from one week at the earliest to three weeks at the latest, to detect whether or not you are pregnant. Early pregnancy test works by detecting the value of human chorionic gonadotropin (HCG), which is excreted into the urine through the blood circulation of pregnant women, and is not easy to detect at first due to the small amount, but can be easily detected by 10-14 days due to the significant increase. Early pregnancy test strips are convenient, quick and easy to use, but it should be noted that not all pregnant women discharge HCG at the same rate and in the same amount, so the use of early pregnancy test strips may also be inaccurate. For women with normal menstruation, HCG may be detected only after the delay of menstruation, and for women with long menstrual cycles, or abnormal ovulation, it may be detected only after about 40 days of menopause. In addition, attention should be paid to the length of urine submerged test strips when testing so as not to affect the results. It should be noted that the early pregnancy test can only be used as a first step in pregnancy screening and not as a method of confirming pregnancy. In order to avoid ectopic pregnancy, pregnant women should go to the hospital for a detailed examination.