This meant that the calendar method predicted ovulation correctly in only one in four women, whereas the ClearBlue Digital Ovulation test (20 test pack) predicted correctly in 99% of women over the same period.
Dr. Jayne Ellis, Director of Scientific and Medical Affairs at SPD Swiss Precision Diagnostics GmbH, Geneva, Switzerland, makers of the test, explained that it consisted of a digital reader and urine test sticks, which could detect the surge in luteinising hormone (LH) that triggers ovulation. "The test stick is held in the urine stream," she explained, "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 now on 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.
"We undertook a comparative analysis of the two methods calendar and the Clearblue Digital Ovulation test using a group of 101 women recruited via local press adverts and a website. The women collected a total of 895 daily urine samples. Ovulation was confirmed by using laboratory analysis of the LH surge, combined with a progesterone rise in the urine. This is a clinically validated method of confirming ovulation," said Dr. Ellis.
The researchers compared the accuracy with which the two test methods predicted the peak fertile days with the standard laboratory method. "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 c
|Contact: Hanna Hanssen|
European Society of Human Reproduction and Embryology