It is not possible to detect pregnancy with test strips for 7 days after intercourse. Because the fertilized egg is still in the fallopian tube and has not entered the uterine cavity, neither blood HCG nor urine HCG can detect pregnancy at this time. Only when the fertilized egg enters the uterine cavity, and the trophoblast cells begin to secrete blood HCG, this time to detect whether the pregnancy, and in the test it is recommended to use morning urine test, because the concentration of HCG in the morning urine will be higher, and strictly in accordance with the operation of the test paper to detect, in order to avoid false negative situation. In addition, do not drink too much water before the test, so as not to cause dilution of urine, which will also appear false negative. So you can’t use test strips to detect pregnancy after 7 days of intercourse, and you can only detect whether you are pregnant after about 15 days of intercourse at the very least.