Digital Test Accurately Predicts Ovulation

A digital ovulation test consists of a digital reader and urine test sticks, which detects the surge in luteinising hormone (LH) that triggers ovulation.

The popular calendar method predicted ovulation correctly in only one in four women, whereas the ClearBlue Digital Ovulation test (20-test pack) predicted ovulation correctly in 99% of women over the same period.

Dr. Jayne Ellis, director of scientific and medical affairs at SPD Swiss Precision Diagnostics (Geneva, Switzerland), makers of the test, explained, "The test stick is held in the urine stream and if the LH levels are elevated, a smiley face appears on the screen. This indicates that the woman is in a highly fertile phase. If there is no hormone surge, a circle is shown on the screen and the woman can test again the following day."

The calendar method, which uses the previous cycle length and subtracts 14 or 15 days to give an estimate of the day of ovulation, is the most commonly used technique for predicting fertility. Available on many websites and mobile phone applications, it is used by 35% of those attempting to conceive. However, up until now it had not been subjected to scientific scrutiny, said Dr. Ellis.

A comparative analysis of the two methods, the calendar and the Clearblue Digital Ovulation test, examined a group of 101 women recruited via local press adverts and a website.

The accuracy with which the two test methods predicted the peak fertile days with the standard laboratory method was compared. "We found that the calendar method was inaccurate in predicting ovulation, and therefore the peak fertile days," said Dr. Ellis. "This is because it uses data from previous cycles which are naturally variable in many women."

Use of the calendar method in women trying to conceive resulted in only one third of cycles where peak fertile days were correctly predicted. On an individual basis, only one in four women trying to conceive would have correctly identified their peak fertile days using the calendar method. In 48% of cycles, the peak fertile period was identified by this method after it had occurred.

By contrast, the Clearblue tests would have been conducted on the day of the LH surge in 77% of the cycles if a seven-stick pack had been used and start day was based on average cycle length. In 6% of cycles, the surge had occurred before the first test day, and in 17% of cycles, it had occurred after the last test was conducted. However, if a 20-stick pack was used, a test would have been conducted on the day of the LH surge in 99% of cycles.

"Like the calendar method, our test is safe and noninvasive," said Dr. Ellis. "But the difference is that it predicts ovulation accurately and therefore gives couples who want to get pregnant the chance to time intercourse correctly and maximize the chances of conception."

The study was presented at the Annual European Society of Human Reproduction and Embryology Conference, which took place in Stockholm, Sweden on July 5-6, 2011.

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Swiss Precision Diagnostics