A pregnancy test detects the concentration of chorionic gonadotropin in the urine of a pregnant woman. There is no way to know for sure how long a dark and light pregnancy will last. If the pregnancy is normal, the two bars will be more visible when the menopause is more than 30 days old, and the color of the two bars will be the same as the color of the bar when it is 40 days old. If a biochemical pregnancy, ectopic pregnancy, the light color deepening will not be very obvious, and some people appear to deepen and then become lighter, this situation may be biochemical pregnancy, or the embryo may have stopped developing. You need to go to the hospital immediately to check the chorionic gonadotropin in the blood and ultrasound, and according to the results of the examination, you can judge whether the pregnancy is normal or not.