The first thing to consider is what type of human pregnancy test you are using. The most common types of human pregnancy tests are home pregnancy tests, urine pregnancy tests, and blood pregnancy tests. Each one contains a different chemical that reacts differently in the body. For example, the urine pregnancy test contains an ingredient called hCG which is produced by the placenta during early stages of pregnancy. This chemical is used to detect the presence of a developing fetus in the womb. These are usually sold at drugstores or grocery stores. On the other hand, the blood pregnancy test uses a chemical called HCG-antibody, which is also produced by the placenta during early stages of pregnancy. This test detects the presence of HCG antibodies in the bloodstream. These are usually sold at pharmacies or online. Home pregnancy tests work by detecting the presence of hCG in the urine. They contain chemicals like nitrocellulose paper, which can change color when exposed to hCG. These are typically found at home improvement stores. Now let's look at how each of these pregnancy tests works.