How does a home pregnancy test work? A home pregnancy test measures the presence of the hormone (H.C.G.) in your urine. H.C.G. is produced shortly after the embryo attaches to the uterine lining. The hormone then builds up rapidly in your body in the first few days following implantation. This test is capable of detecting pregnancy as early as 4 days before your first day of missed period. The further in to the pregnancy you are the higher the levels of H.C.G. get. How accurate are these tests? All our tests have proved greater than 99% accurate in laboratory and consumer studies. How accurate is this test? This test is greater than 99% accurate in laboratory testing. How does a home ovulation test work? When a woman is about to ovulate, her body releases a large amount of a hormone called L.H. (Luteinising Hormone). L.H. is always present in your urine but the levels increase (surge) in the middle of your cycle, causing you to release an egg from the ovary, this process is called ovulation. If the L.H. surge is present, ovulation is likely to occur in the next 24 to 48 hours. These ovulation tests detect the L.H. surge by measuring the amount of L.H. in urine.