Women trying to conceive are better served by a urine test to determine if they are ovulating than the more commonly used calendar method, the makers of the test have said.

“The calendar method is good to help women to start to understand how their cycle works, but if women are really trying to conceive ... it’s not really the best method to use,” said Jayne Ellis, head of scientific and medical affairs at Swiss Precision Diagnostics, which makes the Clearblue ovulation test.

According to a study conducted by the company, the calendar method predicted ovulation correctly in only one in four women, while the test “predicted correctly in 99 percent of women over the same period,” the authors of the study said in a statement.

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 used by about 35 per cent of women, the researchers found. They pointed out that many websites and mobile phone applications offer calculation assistance.