How does a pregnancy test work?
The purpose of an at-home pregnancy test is to detect hCG in pee2. If the hormone is present, a chemical reaction is set off, and the test detects pregnancy. The test will indicate that you are not pregnant if hCG is absent. Depending on the test brand, many tests use two lines to indicate pregnancy and one line to indicate non-pregnancy. Some tests use plus and minus signs. On some digital pregnancy tests, the words “pregnant” or “not pregnant” are displayed in plain sight. Which at least prevents you from squinting and asking, “Is that one line or two? ”
As Ina Garten would say, “How easy is that?” it usually is pretty simple. Most at-home pregnancy tests claim to be about 99% accurate3. At-home tests are extremely helpful because ultrasounds typically cannot identify a pregnancy until a little later in your pregnancy. However, occasionally, other factors can tamper with a pregnancy test’s results and make it appear as though you are pregnant when you are not.
How Common Are False Positive Pregnancy Tests?
It can be devastating to see a positive result and then discover you weren’t actually pregnant. The likelihood of a false positive pregnancy test is extremely low, which is good news for those considering testing. False positive pregnancy tests are extremely uncommon, occurring less than 1% of the time, according to DuMontier, who also clarifies how common they are. Generally speaking, if you notice a false positive pregnancy test, there will be a contributing factor. If not, you can infer that your test was flawed in some way. Related Video.
First, what is a pregnancy test?
To ensure that everyone is on the same page, let’s start with the very basics. A pregnancy test tells you if you’re pregnant or not. Thats simple enough to understand. But it’s understandable if you’re not exactly sure what these devices are looking for when they try to detect pregnancy.
At-home pregnancy tests check for the hormone hCG. Human chorionic gonadotropin, or HCG, is a hormone the body produces during pregnancy. The placenta forms immediately after a fertilized egg adheres to the uterine lining and begins hCG1 production. According to the Cleveland Clinic, although it varies, a urine test can detect hCG 12 to 14 days after conception and a blood test can about nine days after conception. Some particularly sensitive urine tests can even detect a pregnancy earlier. Through 8 to 11 weeks of pregnancy, a person’s hCG level typically doubles every 72 hours. After delivery, it then stays constant and begins to decline. Back to top.