describe how pregnancy tests work
All pregnancy tests work by detecting a certain hormone in the urine or blood that is only there when a woman is pregnant. This hormone is called human chorionic gonadotropin (kohr-ee-ON-ihk goh-NAD-uh-TROH-puhn), or hCG. It is also called the pregnancy hormone. hCG is made when a fertilized egg implants in the uterus.