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How To Choose a Fertility App

How To Choose a Fertility App | Starry-Eyed Pragmatist

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It seems fertility apps are becoming more and more common, which as someone who loves fertility awareness and technology, I think is kind of a cool thing. The trouble is, how do you know the app you’re using to tell you when you’re ovulating is any good? Is one fertility app just as good as another?

Well, here’s the thing, if you are relying on an app to tell you if you are fertile or infertile, then I think you should ask yourself two questions about it.

Two Important Questions

  1. What method protocol or algorithm does the app use to determine fertile and infertile days? It might be a proprietary algorithm and you don’t know the specific rules of the method. That’s ok. See the next question.
  2. What is the scientifically studied effectiveness at preventing pregnancy of that method algorithm that the app is using?

If you can’t answer both those questions, especially the second one, please do not rely on that app as your sole indicator of fertility status, especially if you are trying to avoid (TTA) pregnancy or having trouble getting pregnant.

There are plenty of highly effective Fertility Awareness Based Methods (FABMs) that you can use with an app, which are much more upfront about their method’s scientifically studied effectiveness, and will allow you to make an informed choice. Questions to consider when deciding on a FABM, including app-based FABMs: How effective is this method? Is that level of effectiveness at preventing pregnancy acceptable to you? Will you be able to effectively chart the needed information to follow this method’s protocol?

Useful Fertility Apps

There are apps that are useful for TTA fertility charting. I consider those apps to fall into at least one of three categories:

  • Paper Chart On Your Phone:
    These apps don’t try to predict or interpret your fertility. They are basically just a tool for displaying and allowing you to interpret your own chart, just like a paper chart. Examples of these apps include:

    • Kindara
    • Groove
    • NFP Charting (Billings)
  • Interprets Data Using an Official FABM:
    These apps do interpret your chart for you, but they follow an official FABM protocol to do so. They are transparent about what method and charting rules they are following. Examples of these apps include:

    • Lily (TCOYF or Sensiplan rules)
    • myNFP (Sensiplan rules)
    • FEMM (FEMM rules)
    • Cycle Beads (Standard Days Method rules)
  • Fertility Monitor with a Researched Algorithm:
    These apps use a proprietary algorithm to determine fertility status. However, they are open about the results of the research on how effective the algorithm is at determining fertility status. Examples of these apps include:

    • Natural Cycles
    • Daysy (plus the Daysy monitor)
    • Dot

Now just because an app falls into one of these three categories, doesn’t mean they’re all equal and one is just as good as another. You still need to consider how the use of the app ties into the FABM you have decided to follow to figure out if this is the right app for you. Is there a specific app developed for your specific FABM? Does it help you effectively follow your FABM protocol? Has your FABM instructor recommended you use a specific app? However, if the app does not fall into one of those three categories, then it should not be trusted for TTA fertility charting, with perhaps one exception.

Some apps are still OK to use
as a Paper Chart On Your Phone,
but ignore the fertility status info.

In fairness, some apps kind of straddle the fence between paper chart on your phone and interpreting your data for you by using some unknown or untested algorithm. Kindara, for example, does have some predictive elements, which can (and should) be turned off for TTA. Groove will recognize a temp shift for you, but again, I recommend relying on your own interpretation. There’s also apps that have built-in interpretations that will claim to tell you things like exactly when you ovulate, which in fact, the exact day you ovulate can only be determined by a well time ultrasound, so ignore it when apps try to tell you exactly when you ovulate. But some apps that may tell you unreliable stuff like that may actually also display your data in a useful way and will allow you to effectively read your chart. So, apps like these can be effective tools for avoiding pregnancy if you ignore the fertility status information it’s giving you. Examples of these apps are:

  • OvaGraph
  • Fertilty Friend


Learn to Interpret Your Own Chart

So, it is possible for apps like those to be effective fertility charting tools. However, because they have a unique, proprietary algorithm for interpreting your fertility chart, but they do not have any published research study showing the efficacy of using that algorithm for avoiding pregnancy, I advise to not use the interpretations in these apps for avoiding pregnancy. Use their chart to make your own interpretations using an official FABM. By the way, it is true that OvaGraph is the official app of “Taking Charge of Your Fertility” (TCOYF), but it actually does not strictly use a TCOYF protocol to interpret your chart. Truly, even with apps that use an official FABM to interpret your data, I still recommend learning the rules of that FABM yourself so you can recognize if there is a bug in the app algorithm that incorrectly identifies a day as safe when it shouldn’t be.

Do Not Use These Apps for
Avoiding Pregnancy (TTA)

Here are some popular fertility charting apps that fall very short of the above criteria and should not be used to help you avoid pregnancy:

  • Glow
  • Ovia
  • Clue
  • Flo
  • and many, many more

The truth is the vast majority of apps that will claim to be able tell you your fertility status are relying on a Rhythm Method calculation.

Yes, most apps are using the outdated
Rhythm Method from the 1930s.

The Rhythm Method is not considered an effective, modern FABM. The Rhythm Method is 91% effective with correct use. So, it may be right most of the time for some people with very regular cycles, however it is not right enough to consider it an effective, modern birth control. Another possibility that I’ve also seen is some apps are not even using an actual Rhythm Method calculation. They are just throwing together some random, untested method of their own devising. How effective is it? Who knows! Do you want to be the one to figure that out?

Even more frustratingly, many of these apps allow you to enter individual fertility sign data, like basal body temperature (BBT) and cervical fluid (CF), however they do not alter their fertility status indications based on the additional fertility sign data you entered into the app. It’s still just a Rhythm Method or some other random, unproven calendar based calculation.

What if the app displays a chart?

Can I just use their chart to
interpret my own fertility signs?

Maybe, but likely not. As discussed above, there are some apps that have good charts, which are usable for interpreting your own fertility signs. The trouble is many apps that allow you to enter individual fertility signs will often display a fertility chart for you to see, such as a BBT chart, however, their charts are often displayed in a way that makes it difficult to self-interpret. Some questions to consider: Can you draw a coverline in the app? Can you mark Peak? Can you mark a temp shift? Often the answer is “no.” So, these apps can’t effectively be used as a “paper chart on your phone” either.

This is by no means an exhaustive list of “good” and “bad” fertility apps. Seriously, have you looked up fertility and/or period apps in the App Store lately? The ones I’ve listed barely scratch the surface of vast number of fertility apps that are available for download. Rather than giving you an exhaustive list, what I’m more interesting in doing is giving you the analytical tools to figure out for yourself if any given app that you come across will be an effective tool in helping you determine your daily fertility status.

The bottom line is to be very skeptical
of an app telling you your fertility status.

Your safest bet is to learn to chart and interpret your own fertility signs, and just use an app as a tool to help you do your own interpretation.