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What to look for in a period or ovulation tracker app

What to look for in a period or ovulation tracker app

8 min read

These days, we use apps to manage just about everything in our lives — from ordering food to online shopping to even meeting romantic prospects (well, at least pre-quarantine). It should come as no surprise, then, that many people with ovaries are turning to apps to check in with their cycles and find out when they’re most fertile.

The thing is, there are a lot of apps out there on the market – including one from Modern Fertility.

So… how do you know which ones can actually give you useful insight and which ones are just clogging up space on your home screen? We dug through the data and chatted with Dr. Sharon Briggs, PhD, our head of clinical product and research, to find out.

What are ovulation tracker and period tracker apps?

The Modern Fertility App on iOS

When you open up the app store on your phone, you may see apps referred to as “period trackers,” “ovulation trackers,” or “fertility trackers.” Though these names all differ slightly, they’re all designed to basically do the same thing: provide you with digital tools to help you stay on top of your menstrual cycle.

Many people with ovaries rely on things like calendars, measuring basal body temperature (although this only indicates ovulation after it's happened), and monitoring cervical mucus to track cycles, but apps put all that info in once place to make predictions easier. Knowing exactly how each app does that would require some “reverse engineering,” says Dr. Briggs, but most apps operate on the counting method.

What that means: Apps count the number of days between the last day you reported being on your period and the first day you report being on your next period. Using that info, they can make a prediction of how long your cycle is and when your next period will come.

Apps + LH tests = a winning combination

We might be a little bit biased, but we think apps that allow you to track luteinizing hormone (LH) levels take the predictions to another level. The goal is to help you pinpoint ovulation and the days you’re most fertile.

“Tracking your ovulation using LH strips and logging them in an app adds another layer of data,” says Dr. Briggs. “Specifically, measuring LH can tell you when you’re about to ovulate, so you can correlate that to the other data you are tracking as well. It can give you more confidence that you’re ovulating,” she explains.  

The Modern Fertility App on iOS.

Why is tracking LH so important?

About 24-48 hours before ovulation, the brain triggers a LH surge to prompt the ovary to release an egg and get it ready for fertilization. If you’re able to catch that LH surge with a product like an ovulation predictor kit (OPK), otherwise known as an ovulation test, you can predict when you’ll ovulate with higher accuracy. (It’s important to note, however, that you can sometimes see an LH surge and not ovulate — or more than one surge in the same cycle.)

How this relates to apps: “After the identification of an LH surge, apps typically predict ovulation the next day (the range is 24-48 hours),” Dr. Briggs explains. “The identification of the surge also informs the days in the cycle that were part of the fertile window — meaning there’s a chance to get pregnant during that time.” If you have sex with a partner with sperm or try insemination during that fertile window, the likelihood of conception is highest.

There are also apps on the market that are positioned as “health companions” and ask for details about your emotions, bowel movements, symptoms, and more. While collecting these data points is a great way to check in with your body and track how you’re feeling from cycle to cycle, knowing when you last pooped or what time of the month you feel the most anxious won’t necessarily make it easier to predict your cycle the next time around. If that's your goal, it’s important to assess whether or not “health companion” apps provide the tools for you to do that — beyond recording symptoms and feelings. That said, you can always do that in a separate note or Google doc so you have more info when discussing your cycle with your doctor.

Are ovulation tracker and period tracker apps accurate?

There are two ways to think about accuracy with cycle-tracking apps: accuracy at predicting the next period and accuracy at predicting fertile windows.

In terms of predicting periods, one 2016 study found that only 19% of the apps they analyzed were accurate. For this particular study, an app was considered accurate “if menstrual cycle predictions were based on average cycle lengths of at least three previous cycles, ovulation (when included) was predicted at 13–15 days before the start of the next cycle, and the application contained no misinformation.”

If you’re using the app to help you increase your chances of getting pregnant, explains Dr. Briggs, “What we really care about is how well they predict ovulation in the next 24-48 hours.” Using that metric, apps aren’t all that accurate on their own. In another 2016 study, only three apps were found to be accurate at predicting fertile windows.

That said, apps that log and track ovulation test results provide much higher accuracy. In fact, using products that measure LH predicts ovulation with 95% accuracy. But do you need to measure LH to get the most out of tracking your ovulation with an app? “If someone has a clockwork cycle, then they are very likely ovulating ~14 days before their next period. You don't need to test LH to know that,” says Dr. Briggs. But, she adds, “LH strips are the best way to be sure.” If it’s important to you to accurately identify your fertile window, self-reporting your menstrual history in an app might not cut it on its own.

How do apps stack up when it comes to irregular cycles?

It depends on what type of information you’re looking for and what is irregular about your cycle. If you have cycles that vary in length and you want to predict future cycles, you might not have much luck — that’s because apps typically use an algorithm to make predictions based on your past cycles. If your cycle length varies from cycle to cycle, the app might have a hard time making sense of data that’s all across the board. On the flip side, if your goal is to collect lots of data in one place, then irregular cycles shouldn’t interfere with that.

Similarly, if you have cycles that vary in length and you want to predict your next fertile window, there’s a good chance an app won’t be able to guess the exact number of days before you reach the same point in your cycle again. That’s why apps aren’t always super accurate without the additional input of ovulation test results.

What's the value in using an app to track ovulation?

If you’re trying to get pregnant, an app that allows you to more accurately predict your fertile window is key — meaning one that works with ovulation tests. Why? You have the highest chances of conception by having sex every 1-2 days because it increases the likelihood of overlapping with your fertile window, says Dr. Briggs. “The reality is, for some people, schedules and preferences just don’t always allow for it. So, to give yourself the biggest bang for your buck, you can target sex or insemination to your fertile window with an app — the days you have the highest chance of getting pregnant,” she explains. “In order to do that, you need to know when that happens and that’s where an ovulation tracker app comes into play.”

If you’re not trying to get pregnant, you can still use an app (with or without LH tracking) to better understand your menstrual cycle, says Dr. Briggs. “Your menstrual cycle is a good representation of how your body is working, and not getting a period or having irregular cycles can be a clue that something is going on. This is especially true when your normal cycle (whatever normal is for you) changes,” she explains. “If you don’t have a good feel for your own cycle, it can be hard to identify when things change. Tracking your cycle and ovulation can help you get more clarity into your own cycle.

(Side note: A few apps have even been cleared by the FDA as forms of contraception — but the decision has been viewed by some as controversial after users reported unintended pregnancies.)

Putting it all together: What should you look for in an app?

Whatever your reasons are for tracking your cycle and ovulation, there are a few important things to look for when browsing through app options:

  1. Accuracy: Like we mentioned earlier, not all apps are created equal in this respect. If pinpointing your fertile window with a high degree of certainty is important to you, make sure you’re using an app that has the ability to input data based on ovulation tests. Without the added data from test results, the app’s predictions may only be based on user averages and won’t necessarily reflect the unique nuances of your cycle.
  2. Ease of use: A lot of apps on the market can provide tons of useful insight, but they aren’t that easy to navigate. If recording everything you can is important to you, there are apps that let you do that. If you’re focused on identifying your fertile window, a clean app with only the most important data points might be best for you.
  3. Types of data: Many apps ask for qualitative data instead of quantitative data. In the case of cycle tracking, qualitative data would be user input like days of your period or symptoms experienced. On the other hand, quantitative data would be inputting actual numbers into the app to make predictions more accurate. An app that allows you to enter your LH level on any given day, rather than simply a “yes, I’m ovulating,” or “no, I’m not ovulating” leads to higher accuracy.
  4. How it plays with others: The majority of cycle-tracking apps rely only on user input. Some apps, however, connect with other products, like ovulation tests or thermometers, to allow you to enter quantitative data along with recording your periods. In the end, having this quantitative data allows you to predict ovulation and your fertile window with more accuracy.
  5. Inclusivity: Many apps feature cartoon babies and gendered messaging (not to mention lots of stereotypically "feminine" imagery). If that’s your thing — great! If not, opt for an app that doesn't make assumptions about your reasons for tracking, whether or not you’re partnered up, or if your partner has sperm or ovaries.

What’s coming up next at Modern Fertility

The Modern Fertility App is available now in the iOS App Store. After months of research and development with the Modern Fertility Medical Advisory Board, we’ve launched a brand-new companion app for our Ovulation Test.

The free Modern Fertility App is the one place to digitally log and track your entire cycle so you can plan ahead — whether you’re trying for kids or not. You can use your phone's camera to scan and log your Ovulation Tests ~like magic~ in the app. You can also use the app to track your period, and it’ll give you recommendations on the best days to test for pregnancy.

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Sarah duRivage-Jacobs

Sarah duRivage-Jacobs is a writer and editor at Modern Fertility. She lives with her creamsicle cat, Jasper, in New York City and doesn't believe in the concept of TMI.

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