Clearblue Pregnancy Test with Colour Change Tip offers you 7 signs of certainty: Accurate – No test is more accurate – 99% accurate from the day your period is due. Clear – the only test to give clear (+) and (-) results, It is Fast – gives your result in just 2 minutes, Easy to use – the Colour Change Tip and the control window show the test is working. Sensitive and Early – can be used up to 4 days before your period is due Clearblue Value Pack – Clearblue is also available in a 2 test pack, which gives you great value for money. You may want to test twice if You have tested early and want to retest on the day your period is due. If you are not sure when your period was due. How Does a Clearblue Pregnancy Test with Colour Change Tip Work? When you become pregnant your body starts to produce the pregnancy hormone, human chorionic gonadotrophin (hCG). The amount of hCG in your body doubles approximately every 2 to 3 days, and reaches a maximum at around 7 to 12 weeks into the pregnancy. It stays at a higher than normal level for the rest of the pregnancy, and for up to 3 weeks after giving birth. The Clearblue Pregnancy Test with Colour Change Tip works by detecting the pregnancy hormone in your urine and is over 99% accurate when used from the day your period is due. You can use it up to 4 days before your period is due but if you get a ‘Not Pregnant’ result, you should test again when your period is due. The levels of pregnancy hormone in your urine may not be high enough to be detected yet.The Colour Change Tip and the control window give you extra reassurance by showing you that the test is working. The result window will give you a clear (+) result if you’re pregnant and a clear (-) result if you are not pregnant.