An Australian study of the most downloaded fertility apps has found over half didn't perform well at predicting ovulation — which is exactly what many users are using these apps for.
Less than half of the apps studied predicted the correct ovulation date
Relying solely on an app to avoid pregnancy is a risky game
Apps that take temperature data or urine tests are more likely to be reliable
The findings, by researchers at Eve Health Fertility in Brisbane in conjunction with Queensland Fertility Group, were presented at a Fertility Society of Australia conference this week in Hobart.
The researchers found that between December 2018 and February 2019 there were nearly 400 fertility apps available for Australian women. They analysed the 36 most downloaded of them, which were all on both iTunes and Google Play and in English.
Less than half (42.7 per cent) predicted the correct ovulation date and fewer than one in five (17.1 per cent) predicted the correct estimated due date of a baby, the researchers report.
Many apps also gave incorrect timing for intercourse and incorrect fertile-window calculations.
There was also a "disturbing" lack of reference to scientific evidence — with less than 10 per cent providing references for claims, said researcher Samantha Costa.
But while many of these apps may not be effective, they are wildly popular.
Among adults, they're the fourth most downloaded type of health app and, among adolescents, that ranking jumps to second, Ms Costa said.
"At least 70 per cent of women that are going through some form of fertility treatment rely on these apps to track their cycles," she said.
"And that's really how this study came about — on a daily basis, we asked patients 'do you know where you are in your cycle, do you know whether you ovulate?' And the common theme there is 'let me just check my phone. Let me just check my app'.
"So they are very, very reliant on these applications."
According to Ms Costa, all the apps in this space market themselves as a means of being able to track the menstrual cycle and help with planning fertility. But a lot of them also market themselves as a contraception tool, so it's important that they are reliable.
Ms Costa said the study showed these apps and the claims they made needed to be reviewed by an expert body so consumers knew which they could trust.
What to look for in a fertility app
Figuring out which fertility apps are most reliable isn't as easy as listing them in league table form, because apps come and go, and change as software is updated.
But there are some clues you can look for to help you pick the winners from the duds, according to Robert Norman from the University of Adelaide.
In general, the apps that asked for the most information were the most reliable, said Professor Norman, who was not involved in the study.
In addition to tracking the days of your period, some apps ask users to take their temperature or use urine tests, and these are the best apps.
"The best ones need something added — a thermometer or urine sticks. Just going on a tracker alone is inadequate," he said.
But at the very least, get an app that asks for the length of your menstrual cycle, Ms Costa advised.
"Some of the applications didn't even ask for a cycle length, so they were predicting a cycle based on a 28-day cycle and we know that not everyone has a 28-day textbook cycle," she said.