There are two pregnancy test kits under the Clearblue banner. The Clearblue Easy Digital Pregnancy Test uses words to inform a woman whether she is pregnant. The Clearblue Easy +/- Results with Color Sure Tip test kit indicates a positive result with a plus sign and a negative result with a minus sign. Clearblue asserts this test can give women results 5 days sooner than other pregnancy tests.
Use
Clearblue pregnancy tests work by detecting pregnancy hormone, human chorionic gonadotropin, or hCG. This is produced by the placenta once the embryo attaches itself to the wall of the uterus. A woman tests for this hormone by placing the end of a dipstick in her urine stream for 5 seconds or immersing the dipstick in a container of her urine for 5 to 10 seconds. The woman then lays the test flat or keeps the test strip that was in the urine stream pointing down. Results are shown 2 minutes later. The digital test kit will have either the word "pregnant" or the words "not pregnant."
Time Frame
There's always the possibility that early testing will be done too soon to get accurate results despite manufacturer claims because the embryo's implantation most often occurs 6 to 12 days after ovulation, advises Fertility Plus. Clearblue Easy claims its plus and minus sign product can be used 4 days before a woman expects her period, giving her a 5-day lead over waiting to miss a period to test.
Clearblue cites its own clinical testing results, saying that 53 percent of pregnant women were able to gain that 5-day lead. The company says 74 got results 4 days quicker; 84 percent got results 3 days quicker and 87 percent get results 2 days quicker. On the digital test, Clearblue says 55 percent of pregnant women got positive results 3 days prior to the date their periods were due. Some 87 percent got such results 2 days prior, and 92 percent got results 1 day prior.
Expert Insight
Clearblue falls behind First Response for early detection of pregnancy. First Response got top ratings by "Consumer Reports" and detects hCG levels of 6.5 mIU, or thousandths of an International Unit. Clearblue has the next-best level of detection among home pregnancy test kits at 25 mIU. The 6.5 level is about the level of hCG that is present when an embryo attaches to the uterine wall.
The level of hCG doubles approximately every 2 days. However, the Clearblue digital test made the top two at the Consumer Search product review website. The review cited the ease of seeing the words "pregnant" or "not pregnant" instead of needing to interpret pink or blue lines. The main downside Consumer Search cited was that the test is not as sensitive as others due to the need to reach the 25 mIU level.
Problems reported by customers include getting an image of a book instead of a result, which is a malfunction reading, a dead battery, and false-positive readings. In comparison, the First Response Early Result kit is more sensitive, but many testers say it's more difficult to interpret the lines, according to Consumer Search.
Considerations
The most common reasons for false-positives in pregnancy test kits like Clearblue are having traces of protein or blood in the urine and use of some prescription drugs, including promethazine that's used to treat allergy symptoms or diuretics. A damaged or expired kit also can lead to a false-positive, according to the Mayo Clinic. Taking the test within a month of miscarriage also can cause a false-positive because it takes time for hCG levels to reach zero again, advises Fertility Plus. Incorrect negative results are most often caused by taking the test too early, incorrect timing of the test such as waiting longer than 15 minutes to place the kit's dipstick in urine, or diluted urine caused by drinking too much liquid prior to testing, according to the clinic.
Potential
Home pregnancy test kits like Clearblue are an extremely reliable method of testing for early pregnancy when used in a laboratory setting by skilled technicians, being accurate 97.4 percent of the time. These are less accurate, however, when used by customers who buy the kits due to limitations in customers' abilities to perform the tests, according to the journal "Archives of Family Medicine." Manufacturers do not publish the results of trials with actual customers, so there is no proven accuracy rating for real-life use. Women who have a negative result should wait 1 week and then retest, while women who have a positive result should schedule a doctor's appointment as soon as possible, the journal reports.
