How pregnancy tests work
Even if you are not a parent yet, chances are you know what a pregnancy test looks like. Let's find out how they work.
Pharmacies carry different types of home pregnancy tests. However, they all work much the same way, by looking for the human chorionic gonadotropin (hCG) hormone which starts to develop in a woman’s system from the beginning of pregnancy and doubles every few days in the first weeks [1, 2].
At-home pregnancy tests are accurate when used correctly: a positive result can be trusted, but a false negative is possible, most often when the test is done too soon after conception or not as the instructions say [3]. A person’s best bet is to closely follow the instructions on the test and wait until they miss their period; if the result is negative and the period still doesn’t come, they can test again a few days later and see a doctor if the second test is also negative. Keep in mind that some tests can detect lower levels of hCG than others; that information is usually printed on the package.
Pregnancy can also be confirmed via a blood test. These are usually ordered if the doctor needs to know the exact levels of hCG, or if they don’t want to wait until a missed period to know if conception was achieved. These situations can be common in couples undergoing fertility treatment or who have a history of miscarriages [2].
