Which hormone is primarily detected in pregnancy tests?

Human chorionic gonadotropin (hCG) is the hormone primarily detected in pregnancy tests because it is produced by the developing placenta shortly after a fertilized egg attaches to the uterine lining. The presence of hCG in a woman's urine or blood is a reliable indicator of pregnancy, as it typically rises rapidly in the early stages of gestation. Pregnancy tests are designed to specifically recognize this hormone, allowing for quick and accurate detection of pregnancy.

Other hormones such as estrogen and progesterone do play significant roles during pregnancy, but they are not specific markers for pregnancy detection like hCG. Testosterone, on the other hand, is primarily associated with male reproductive functions and does not indicate pregnancy. Thus, hCG stands out as the crucial hormone utilized in pregnancy tests to confirm whether a woman is expecting.