Pregnancy Tests and How They Work
Human chorionic gonadotropin (hCG) is detected in urine by home pregnancy tests. After implanting into the uterine lining, a fertilized egg produces hCG. In order for a pregnancy test to be positive, sperm must not only fertilize an egg, but the egg must also implant in the uterus.
When an embryo begins to release hCG, it first appears in the mother's bloodstream, followed by her urine. The hCG hormone is detected in urine by home pregnancy tests. A woman can use a pregnancy test at home by collecting her urine in a cup, dipping a test strip into it, or peeing directly on the test. If the test is positive, two lines appear; if the test is negative, only the control line appears. A positive pregnancy test is indicated by any line, no matter how faint.
Digital home pregnancy tests use the same method and technology as traditional home pregnancy tests, but they read the lines for you and give you a definitive result of "pregnant" or "not pregnant" rather than requiring you to interpret the line or lines.
When Can You Get a Pregnancy Test?
A blood pregnancy test is usually unnecessary because home tests are sensitive and accurate. However, your provider may think it is a good idea to test your blood for pregnancy hormones in a few cases.
Negative Tests and Late Period
If your period is more than a week late and you have negative home tests, you should consider getting a blood test. Your doctor may also want to look for other causes of your delayed period in your blood.
Treatments for Infertility
Because many fertility medications and shots contain hCG and can cause a false positive home pregnancy test, your doctor may monitor your hCG levels in your blood if you are undergoing fertility treatments. If your hCG levels continue to rise, you are almost certainly pregnant!