How do pregnancy tests work?
Pregnancy tests look for a special hormone in the urine or blood that is only there when a woman is pregnant. This hormone, human chorionic gonadotropin (hCG), can also be called the pregnancy hormone.
The pregnancy hormone, hCG, is made in your body when a fertilized egg implants in the uterus. This usually happens about 6 days after conception. But studies show that the embryo doesn't implant until later in some women. The amount of hCG increases drastically with each passing day you are pregnant.
How many types of pregnancy tests are there?
There are two types of pregnancy tests. One tests the blood for the pregnancy hormone, hCG. The other checks the urine for this hormone.
The blood test checks for pregnancy. Blood tests can pick up hCG earlier in a pregnancy than urine tests can. Blood tests can tell if you are pregnant about 6 to 8 days after you ovulate (or release an egg from an ovary). A quantitative blood test (or the beta hCG test) measures the exact amount of hCG in your blood. So it can find even tiny amounts of hCG. This makes it very accurate.
The urine test checks for pregnancy. Qualitative hCG urine tests just check to see if the pregnancy hormone is present or not. So it gives a yes or no answer.