A very dark second bar on a pregnancy test usually indicates pregnancy. However, false positives caused by expired pregnancy tests or incorrect use of pregnancy tests cannot be ruled out. It is recommended that a human chorionic gonadotropin (HCG) test be taken to determine whether or not a woman is pregnant. A pregnancy test measures the concentration of human chorionic gonadotropin in a woman’s urine, a hormone that is secreted after the formation of a fertilized egg. A pregnancy test can detect pregnancy as early as 12 to 14 days after intercourse. Under normal circumstances, as long as two bars appear, it means that you are pregnant. Moreover, the darker the color of the second line, the higher the concentration of human chorionic gonadotropin and the longer the pregnancy lasts. However, if the pregnancy test is outdated or used incorrectly, it may also show false positives. Therefore, when the pregnancy test stick detects two bars, you can go to the hospital for a specific test of human chorionic gonadotropin indicators in the blood, you can determine whether you are really pregnant, and you can also roughly determine the time of conception, for the subsequent arrangements for the time of the obstetric examination. So, under normal circumstances if the pregnancy test shows two bars, then it means that conception has been successful. If the second bar is very dark in color, it is a strong positive.