Varuna Srinivasan, MBBS, MPH: National Center for Health Research.
There are several apps currently available to help a woman track her fertility in the hopes of getting pregnant. These include Kindara, Glow, Groove, Fertility Friend, Clue, Conceivable and Ovia – all help a woman track the days when she is most fertile. Ranging from $0.99 for the app to $45/month, each app provides a unique service of tracking fertile days, using basal body temperature chart, ovulation calculator, menstrual calculator or simply serving as a fertility planning journal. 1
Of course, if you can track the days you are most fertile, the same information can be used to try to prevent pregnancy. On August 10, 2018, the FDA approved Natural Cycles as a contraceptive tool.2 This Swedish-based app, which was already available in Europe, costs $75 per year and comes with a thermometer. This app uses a statistical algorithm that calculates fertility from user-entered information, including basal body temperature, and assigns days as “red” or “green.” “Red” days represent days on which it is unsafe to have sex if a woman wants to avoid getting pregnant. Women are advised to use other forms of contraception, such as condoms, pills or abstinence, on these days. “Green” days are considered “safe” days on which women can have unprotected sex with their partners. 3
Natural Cycles claims on their website that the reliability of the application is comparable to that of a condom and has a method failure rate of 7%, meaning only 7 women out of the 100 women using the app will get pregnant.
That sounds effective compared to, for example, condoms (which has a method failure rate of 18%). Fertility awareness methods or ‘Calendar’ Methods, methods that rely on a combination of basal body temperature recordings and cervical mucus based on a woman’s menstrual calendar, are known to have a method failure rate of 25%.4
But is the 7% method failure rate listed for Natural Cycles accurate? There have been reports of more than 3 dozen women in Sweden getting pregnant while using this app. More on this can be found here.
In 2018, Natural Cycles was banned from being advertised in the UK due to false claims of efficacy. The app advertised itself to over 100,000 UK users as being highly accurate in preventing pregnancy and as a form of “clinically tested alternative to birth control”. More on the reason for this ban in the UK can be found here. They point out that 68 women out of 1,000 will become pregnant during a year of use if the app fails, they have unprotected sex, or do not use contraception on a red day. Even if used perfectly, 10 women out of 1,000 would become pregnant after having unprotected sex on a falsely-attributed green day, or if contraceptive methods failed during intercourse on a red day.
While fertility apps that are aimed to help you get pregnant are not entirely accurate either, they are help women keep track of their last menstrual periods, fertile days, and as a journal to keep track of important fertility tests. For the, the benefits of using the app far outweigh the risks. That does not seem to be true of Natural Cycles.
The Bottom Line
All fertility apps are heavily dependent on users putting accurate information into the system. Women using any of these apps would need to be diligent in entering their information accurately and on time. Our advice and recommendation is that whether you are trying to conceive or trying to avoid pregnancy, consult with your gynecologist to find the right tools to help you achieve your goal. However, Natural Cycles is not a reasonable alternative to more proven contraception.
- Healthy Women, Fertility Apps: Which One Is Best for You? www.healthywomen.orghttps://www.healthywomen.org/content/article/fertility-apps-which-one-best-you
- Food and Drug Administration, DE NOVO CLASSIFICATION REQUEST FOR NATURAL CYCLES, www.fda.gov,https://www.accessdata.fda.gov/cdrh_docs/reviews/DEN170052.pdf
- Natural Cycles, Digital Birth Control, www.naturalcycles.com,https://www.naturalcycles.com/en-us/birthcontrol/howitworks/
- Food and Drug Administration, Birth Control, www.fda.gov, https://www.fda.gov/forconsumers/byaudience/forwomen/freepublications/ucm313215.htm