Is a faint and a dark line on a pregnancy test stick a sign of impending menstruation?

Generally, a pregnancy test stick showing one dark line and one light line is not a sign of an upcoming menstrual period, but rather may indicate pregnancy. If you experience any discomfort, please seek medical attention promptly and undergo symptomatic treatment under the guidance of a professional physician. Detailed explanation is as follows:

Pregnancy test sticks determine whether a woman is pregnant by detecting the level of human chorionic gonadotropin (hCG) in the urine, which is unrelated to menstruation. Human chorionic gonadotropin is a hormone secreted by the embryo after pregnancy. In early pregnancy, the concentration of hCG gradually increases. A dark line indicates that the hCG concentration is sufficiently high, usually indicating pregnancy. A light line suggests a lower hCG concentration, which may indicate an early stage of pregnancy or that the test was performed too early. If the test result shows one dark and one light line, it generally means that the woman is pregnant, but due to possibly lower hCG levels, the second line is less distinct than the first.

In addition, if the pregnancy test stick is expired or improperly stored (e.g., exposed to moisture), it may affect the accuracy of the test result, potentially leading to a false-positive result with one dark and one light line. Similarly, excessive dilution of the urine or improper testing procedures may also lead to inaccurate results.

Changes in the menstrual cycle and signs of an impending period usually include symptoms such as breast tenderness, abdominal discomfort, and mood swings. These symptoms do not affect the accuracy of a pregnancy test result.