Final answer:
Human chorionic gonadotropin (hCG) is the hormone detected by pregnancy tests, which confirms pregnancy by maintaining the corpus luteum for progesterone production.
Step-by-step explanation:
The hormone that pregnancy tests detect to indicate pregnancy is called human chorionic gonadotropin (hCG). This hormone is crucial for pregnancy because it is produced by the cells that will become the placenta. hCG helps to maintain the corpus luteum, which is responsible for the production of progesterone during early pregnancy. Progesterone is vital as it prepares the lining of the uterus for the fertilized egg and helps maintain the early stages of pregnancy. When a woman takes a pregnancy test, the test line indicates the presence of hCG in her urine, confirming pregnancy. The control line, on the other hand, ensures the test is working correctly.