All home pregnancy tests detect the ‘pregnancy hormone’, human Chorionic Gonadotropin (hCG) in urine. In pregnancy, hCG is produced first by the fertilized egg and later the placenta. A fertilized egg typically implants into the lining of the uterus (womb) as early as 6 days after fertlization, when tiny amounts of hCG start to appear in the mother’s blood and urine. Though hCG levels are very low at first, the level rises rapidly and predictably in the first weeks of pregnancy.¹

Even though hCG levels are very low at first, they increase rapidly in the first weeks of pregnancy.
If a pregnancy test detects hCG, your result will be positive and you can be confident that you are pregnant.
If the test is negative, but you tested before the day of your expected period, then there is the possibility you could still be pregnant but your hCG levels were too low for the test to detect. You should test again in a few days’ time, or when your period is due. If you get a negative result on or after the day you expect your period, but still think you might be pregnant, see your doctor.

What are the different types of pregnancy tests?

Urine pregnancy tests

Urine pregnancy tests (also called UPTs) conducted at a doctor’s office work just like home pregnancy tests do: they detect the presence of hCG. The main difference? Unlike a home pregnancy test, you’ll need to make an appointment with your healthcare provider, who will perform and analyze the test. Typically, a nurse will provide you with a plastic cup with a lid. You’ll pee in the cup and then give your sample to the nurse. Just like with a home pregnancy test, you’ll know the result of a urine pregnancy test performed at the doctor’s office fairly quickly as well.

Blood pregnancy tests

Blood pregnancy tests are generally quantitative. If your doctor wants to monitor your hCG levels, they will order a quantitative blood pregnancy test, which measures the amount of hCG in your blood. Most U.S. doctors monitor hCG levels if you have a history of miscarriage or you’re showing symptoms of a possible early pregnancy loss⁶. Blood pregnancy tests need to be analyzed and the doctor will read the results, so you may not get the results the same day.

How accurate are pregnancy tests?

When it comes to taking a pregnancy test, all Clearblue® tests are over 99% accurate at detecting pregnancy from the day you expect your period⁴. Some tests can also be used as early as 6 days before your expected period. Just find the right home pregnancy test for you and your needs, and make sure you follow the instructions carefully.

When can I take a pregnancy test?

After the egg is fertilized, it travels to the uterus (womb) and begins to implant in the uterine wall. If implantation is successful, tiny amounts of the pregnancy hormone, hCG, can start to appear in your urine from around 7 – 9 days after ovulation. It is this hormone that all home pregnancy tests detect. Some early pregnancy tests, such as the Clearblue® Early Digital Pregnancy Test and the Clearblue® Early Detection Pregnancy Test, can tell you whether you are pregnant as early as 6 days before your missed period (5 days before you expect your period)^2,3.

No matter when you test, you can be confident in the accuracy of a “Pregnant” result with any Clearblue® Pregnancy Test.⁴

But if you are testing early, before your period is due, you should be aware that even if your result is not pregnant, you may still be pregnant. This is because human Chorionic Gonadotropin (hCG) levels vary from woman to woman, and there may not yet be enough of the hormone for the test to give a positive result.

The day of your expected period is the day your period is due to start. If you still haven’t got your period the next day, this is the first day of your “missed period”. If you see instructions in the leaflet telling you, you can take a test 5 days before expected period, this is the same as 6 days before your missed period. The Clearblue® Early Detection Pregnancy Test, can detect hCG as early as 6 days before your missed period³.

You can use the calculator below to check when you can take a pregnancy test. Most women have menstrual cycles that vary in length from cycle to cycle, which is perfectly normal. If your cycles tend to vary, you should use the longest cycle you’ve had in the last 6 months, in the calculator below.