The vast majority of clinically fertilized eggs do not show vaginal bleeding when they are in bed, so it is recommended that if a blood test for HCG is taken 15 days after intercourse, you can find out if you are pregnant. If two red lines appear and the color is the same, it indicates pregnancy. If there are two red lines and one of them is lighter in color, this is an indication of possible pregnancy and it is recommended to collect morning urine after 3 days and do another test. If the two red lines are still dark and light after 3 days, you must go to the hospital to have a blood test for HCG to rule out the possibility of ectopic pregnancy.