Definition - What does Pee on a Stick (POAS) mean?
Pee on a stick (POAS) is a slang reference to the use of an at-home pregnancy test. The test comes in the form of a stick with a small screen near one end and a absorbent tab on the other end of the stick. A woman who suspects she is pregnant pees on the absorbent end and then lets the test sit for a length of time as indicated by instructions for the test. After the time has passed, the screen will indicate pregnant or not.
FertilitySmarts explains Pee on a Stick (POAS)
An at-home pregnancy test relies on levels of human chorionic gonadotropin (hCG). This chemical is a naturally occurring substance that is produced during pregnancy by the placenta. hCG finds it's way into the bloodstream and urine almost immediately after an embryo implants itself into the walls of the womb. Most tests are 99% effective when taken on the day a period would normally start. Taking the test earlier may alter the effectiveness. It is also commonly recommended to take the test in the morning due to the stronger concentration of the hCG in the body.