Here are answers to some of the most common questions about pregnancy tests.
What is a pregnancy test and how does it work?
Pregnancy tests are designed to tell if your urine or blood contains a hormone called human chorionic gonadotropin (hCG). This hormone is made right after a fertilized egg attaches to the wall of a woman's uterus.
This usually happens -- but not always -- about 6 days after fertilization. If you're pregnant, levels of hCG continue to rise rapidly, doubling every 2 to 3 days.