The app is called Natural Cycles and uses a woman's natural menstrual cycle in creating an algorithm for their body to predict their fertile days. The downside is that it will take a lot of dedication on the woman's part to be accurate and correct. Women will be required to take their temperature using a body basal thermometer every morning as soon as they wake up and keep an accurate record of their menstrual cycle. Body basal thermometers are more sensitive than a regular thermometer, and they are more expensive.
Natural Cycles will then calculate a woman's highest days of fertility based on this information. Depending on what you are hoping for, you either do the deed a lot on these days or hold off completely. The app will cost $79.99 annually and includes a body basal thermometer.
Mercury News had all of the tech info needed for this new, one of a kind app. It differs from other period trackers because it uses more information and creates a personalized algorithm as opposed to period tracking apps that use the same baseline for all of their downloads.
Initial clinical studies for Natural Cycles were generally successful. Of 15,500 women who used the app perfectly as directed for an average of 8 months, only 1.8% of them became pregnant. This is the failure rate. The typical use failure rate was 6.5% and included women who weren't so diligent with the app, or had sex on fertile days anyway.
Still, those are pretty impressive numbers considering the birth control failure rate is even higher. According to the CDC, the birth control failure rate is 9% and condoms fail 18% of the time. The IUD failure rate is the only comparable one to Natural Cycles at just 1%. Still, a lot of women don't want any sort of hormone and foreign object in their body. This app can be an alternative.
The huge downside of Natural Cycles is keeping up with your tracking. While it is similar to the "rhythm method", which also depends on body temperature, you need to be sure you're recording your temperature at the same time every day when you first wake up. You also need to record your period start date and end date.
It can be a lot to keep up on and can be easily forgotten on a busy morning. Consistency is key here which can lead to a failure in more ways than one. We'd imagine this app may be better for planning a pregnancy than preventing one.