How pregnancy tests work

Pregnancy tests check your urine or blood for a hormone called human chorionic gonadotropin (hCG). This hormone is produced during pregnancy and can be detected as early as 10 days after conception, when a fertilised egg attaches to your womb.

If hCG is found in your blood or urine it is highly likely that you are pregnant.

Home pregnancy tests

Home pregnancy tests, which can be bought over the counter from a chemist or supermarket, test your urine. There are different types. Read the instructions carefully before doing a home pregnancy test. It is best to collect the urine sample first thing in the morning, before you have drunk a lot of fluid, or there might not be enough hCG to give a positive result.

With most home kits, you either hold the end of a chemical dipstick in your urine stream or collect the urine in a container and test it. The dipstick tests for hCG and uses colours or symbols to show whether or not you are pregnant. Digital dipsticks may state ‘pregnant’ or ‘not pregnant’ and can be easier to read.

Most pregnancy tests can detect hCG in your urine on the first day your period is due. If the test is negative but your period still doesn’t come, you could try re-testing in a few days. If the test is positive it is most likely that you are pregnant. It will only be in very rare circumstances that you will get a positive result that is incorrect or false.

To get the most reliable results, wait until at least a week after your expected period before testing. Then the amount of hCG should have built up in your body if you are pregnant. Some digital kits are more accurate than traditional test kits.

Repeat the test a few days later. Always consult your doctor or clinic to confirm that you really are pregnant.

Pregnancy tests performed by a doctor

Nurses, doctors or specialists can do either urine or blood tests to confirm whether you are pregnant. The urine tests are similar to the home ones.

The blood tests for pregnancy are more sensitive and accurate than urine tests. They can detect whether the hormone is present in your blood and how much hCG there is.

Testing the level of hCG and the rate at which it increases is one way your doctor can tell if your pregnancy is normal. For example, an extremely high hCG level may be a sign you are expecting twins or have some disorder.

It’s important to consult a medical professional early in your pregnancy.