Editor's update: Since this article was published, the FDA has approved the Natural Cycles app and basal body thermometer to prevent pregnancy as a Class II medical device. We know of at least two studies that have looked at the accuracy of period and fertility tracking apps. Here's what they found.
In the last few years, one of the most ancient contraceptive methods has taken a modern turn. At last count, there are over 200 fertility awareness method (FAM) mobile applications (“apps”) for measuring, monitoring, and tracking women’s cycles. Before we dive into the apps, here’s an oh-so-brief overview of FAM.
Practice pearls for patients using FAM
To prevent pregnancy, FAM depends on women being aware of their fertile and infertile periods. Users typically monitor basal body temperature and cervical secretions, count calendar days, and may use over-the-counter ovulation tests. FAM has gotten a bad rap, largely due to the Roman Catholic Church’s advocacy of the rhythm method. But when practiced carefully, FAM can have an unintended pregnancy rate as low as 2 to 5%. (More typically, the failure rate is about 12 to 25% annually.)
What, then, does careful practice mean? What can we recommend to patients? Here are some principles to keep in mind:
Understand the biological signs of fertility. The nuances of cervical secretion changes are beyond the scope of most sex ed classes. Your advice and resources like the classic Taking Charge of Your Fertility can help. Ultimately, it’s a good idea for women to take a couple of cycles to get to know their own bodily changes before relying on FAM alone to prevent pregnancy.
Know the backup plan. For some women and couples, periodic abstinence is their preferred backup. Others may use condoms or other barrier methods, the effectiveness of which can be enhanced through the use of spermicides. A growing body of research also points to withdrawal as a common method whose efficacy has perhaps been underestimated. Patients may want to have emergency contraception (EC) on hand for use as needed, or know where they can receive a copper IUD as EC. (Bonus: A copper IUD is the most effective EC option but also works as highly effective birth control for up to 12 years!)
Track fertile and infertile periods carefully. Though graph paper and a pencil have been successful for women and couples for decades (if not centuries), newer technologies may be helpful here.
It’s also helpful to remember that not all patients experience pregnancy planning as a categorical decision. Pregnancy ambivalence, or simply being open to pregnancy, is common among women and men of all ages, and FAM requires buy-in from both partners. Explore with your patients what they might do if they became pregnant. And if you want a deeper dive on FAM, the classic book Contraceptive Technology has an excellent chapter.
Apps for FAM
So, what about those hundreds of apps? There have been a few articles in the popular press that describe these apps and report on what they call the “return of the rhythm method.” These are interesting but don’t necessarily speak to the apps’ accuracy or user-friendliness. Below are some factors to consider in evaluating apps. You can take yourself on a self-guided tour of some of the most popular ones or simply recommend to patients that they consider the following questions:
Is the app effective and evidence-based? To us as providers, this is the crux of the matter. Unfortunately, this is one of the hardest features to evaluate. Most apps’ websites are silent or vague on this issue. Clue bills its app as “scientific,” but does not offer additional information about how its algorithm works or how accurate it is. NaturalCycles offers the most information about its scientific basis, and it sounds impressive: They report that “in 202,544 days of its service being used there have been zero unwanted pregnancies.” However, this is based on proprietary data, not a peer-reviewed publication, and most apps do not offer similar data with which to compare. iCycleBeads is based on the classic CycleBeads method of implementing the Standard Days Method, which has been well-evaluated.
Are you willing to pay for an app? Some apps shown as “free” lock their best features behind a paywall. For patients who don’t want to pay for an app, My Days is free and simple to use, as is Clue.
Is the app customizable? If you can personalize your music apps, why shouldn’t you be able to personalize something as personal as fertility? The popular app Glow allows users to choose which data points they wish to monitor and allows them to enter symptoms like breast tenderness. (Note that Glow is geared mostly at users trying to become pregnant). If your patient has irregular cycle length, her app must be able to account for this. Many, including iCycleBeads, cannot.
Is the app intended for pregnancy prevention, pregnancy planning, or both? One factor that makes FAM unique among family planning methods is that it can be used both to prevent and to plan pregnancy. This can be convenient and empowering for patients, who can continue to use FAM as their fertility desires change. However, for those focused on avoiding pregnancy, the apps geared at pregnancy may produce some discomfort. Fertility Friend, for instance, is mainly designed for women planning pregnancy. Kindara and OvuView (available for Android only) function well for both prevention and planning.
Ultimately, in the absence of scientific literature evaluating or comparing the apps (multi-arm RCT, anyone?), it’s impossible to make a truly evidence-based recommendation. But highlighting the above factors for patients and familiarizing yourself with a few good apps is a safe and appropriate adjunct to self-knowledge and clinical consultation.