Human chorionic gonadotropin (hCG) is a hormone produced during pregnancy. It is secreted by the placenta shortly after a fertilized egg attaches to the uterine lining. hCG plays a crucial role in maintaining the production of progesterone, which is essential for a healthy pregnancy. In addition to its role in pregnancy, hCG is also used in medical treatments. It can be administered to stimulate ovulation in women and to increase testosterone production in men with certain conditions. hCG is commonly detected in pregnancy tests, as its presence indicates that a woman is pregnant.