How pregnancy tests work

Pregnancy tests work by checking for a specific hormone in your body called human chorionic gonadotropin (hCG). This hormone is only produced after a fertilized egg has attached itself to the lining of the uterus. Once that happens, your body starts releasing hCG into your blood and urine.

Most home pregnancy tests use urine. You either place the test strip in your urine or hold it in your urine stream. If hCG is present, the test reacts to it and shows a result, usually as lines, a plus sign, or even words like “pregnant” or “not pregnant,” depending on the type of test.

In the very early days, hCG levels are still low, which is why timing matters. If you test too early, the hormone might not be strong enough to detect yet, and you could get a negative result even if you’re actually pregnant. That’s why it’s often recommended to test after a missed period or a few days later for a more accurate result.

There are also blood tests done in hospitals or clinics, which can detect even smaller amounts of hCG and confirm pregnancy earlier than urine tests.

It’s important to follow the instructions on the test carefully, because things like using too much or too little urine, or checking the result too early or too late, can affect accuracy. If you’re unsure about your result, repeating the test after a few days or speaking with a healthcare professional can help you get clarity.