As reliable as an ultrasound scan Clearblue Pregnancy Test with Weeks Indicator is the only test to date that is as accurate as an ultrasound scan at determining the week of pregnancy. For optimal certainty, the Smart Dual Sensor not only tells you in text form whether or not you are pregnant, but also tells you the week of pregnancy.* The advanced digital display means you don't have to waste time interpreting lines, so you get reliable, clear results even in the early stages of pregnancy. Benefit from over 99% reliability from the day your period is due. The only test that tells you how many weeks ago you conceived. *Result in weeks was 97% accurate with later ultrasound determination of conception date. Based on studies with 187 women and comparison of results (1 to 2, 2 to 3, 3+ since conception) with date determination by ultrasound in the range of +/- 5 days.