A self-administered test for detecting low levels of T4 hormone during pregnancy. There is an important correlation between hypothyroxinemia during pregnancy, and the appearance of neurodevelopmental disorders in the newborn. Therefore, it is highly advisable to keep records of the levels of T4 hormone during the first months of pregnancy. The test consists of a device, similar to a pregnancy test, that indicates T4 levels below the safe range, enabling time-bound action in case the levels are too low.