The Clearblue pregnancy test with week indicator is the first and only test that is as accurate as an ultrasound examination to determine the duration of pregnancy*. The smart dual sensor not only tells you whether you are 'pregnant' or 'not pregnant', but also lets you know how long you have been pregnant. The number of weeks since conception is shown as 1-2, 2-3 or 3+. This test can be used 5 days before your missed period (maximum 4 days before your period is due). In laboratory tests, 98% of 'pregnant' results were detected the day before menstruation was due, 97% were detected 2 days in advance, 90% were detected 3 days in advance and 65% were detected 4 days in advance. (* 'weeks' indicates a 97% agreement with later dating of the pregnancy by means of an ultrasound examination. This is based on a study of 187 women in which the results were compared with ultrasound examination). Data on file johnson, sr Et al. Fertility and sterility Dec 2013 (vol. 100, issue 6, pp 1635-1641. our helpline advisors are available from 8am-4pm for more information about this product or answers to your questions. * The first and only pregnancy...