Most fertility apps get it WRONG, scientists say

Women using fertility apps and websites to work out when they are most likely to get pregnant could be getting bad advice, a study has warned. 

Tests were carried out on 20 websites and 33 apps designed to help predict a woman's fertility window - the days before ovulation when having sex is most likely to result in conception. 

Usually,  a woman with a standard 28-day menstrual cycle will ovulate around day 15, which would also be the last day of a six-day fertile window.

While most reliably predicted the day of ovulation, only four provided the correct fertile window the study found.

This suggests thousands of women are being wrongly informed about when they are most likely to conceive. 

Dr Robert Setton, a researcher at Weill Cornell Medicine and New York Presbyterian Hospital, said it was vital women understood when their fertile window is.

'Before using any website or app, women need to understand that the actual fertile window consists of the day of ovulation plus the preceding five cycle days,' he said. 

'They can use the app or website to help them predict their ovulation date and then use that as a guide for the rest of the fertile window.'

Dr Setton and colleagues tested all of the websites and apps with the same case - a woman with a 28-day menstrual cycle and four days of menses, whose last period started January 1.

In this test case, 80 per cent of websites and 87 percent of apps that predicted the day of ovulation correctly said it would occur on January 15, the study found.

But just one website and three apps correctly predicted a fertile window of January 10-15.

The only accurate website for the fertile window was babymed.com, Dr Setton said. Among the apps, the ones that got it right were iPeriod, My Days and Clue.

The findings suggest that women should be cautious about relying only on websites and apps to predict the best days each month to try to conceive, the authors conclude in Obstetrics and Gynecology.

Couples using an incorrect fertile window from an app or website to time intercourse may end up having sex too soon or too late in the month to conceive, the authors note.

Researchers admitted they only included free apps and websites which limits the study.  

It did not examine how often couples decide to have sex based on the fertile window suggested by these tools, or explore how often couples conceived.

Even so, Deborah Lupton, a researcher at the University of Canberra in Australia who wasn't involved in the study, said women may want to rely on alternatives to determine their fertile window each month.

They can do this by tracking some changes in their bodies that occur around ovulation, including a slight spike in body temperature and an increase in vaginal discharge as the cervix releases thin, clear mucus.

'Once women do this for a while, they should get a good sense of where in their cycle they ovulate,' Professor Lupton said.

'These apps and software tools are not likely to be effective for women who either are trying to conceive or using these tools to avoid conception.' 

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