A pregnancy test stick showing one dark and one light is a weak positive, the possibility of pregnancy is higher, but also can not be ruled out that the quality of the test stick is not qualified. 1. pregnancy: when a woman is conceived for a short period of time, the level of human chorionic gonadotropin (HCG) in the body will be on the low side, which may lead to the pregnancy test stick to show a dark and light. In addition, ectopic pregnancy can also make the body HCG elevated, may appear pregnancy test sticks show a dark and light. 2. Failure of the quality of the pregnancy test stick: When the quality of the pregnancy test stick used by the woman is problematic, it may also cause the pregnancy test stick to show one depth and one light. Therefore, a pregnancy test stick showing one dark and one light is not certain that you are pregnant, and whether it is intrauterine pregnancy, it is recommended that you can measure several times or go to the hospital to take blood to check the HCG level and ultrasound to clarify whether you are pregnant or not.