The rise of “femtech” and the proliferation of fertility apps has been accompanied by increasingly worrisome headlines about the accuracy and privacy of these apps. As Silicon Valley seeks to capitalize on women’s health, it is estimated that femtech could become a $50 billion industry by 2025. Currently, the market boasts over 100 fertility-tracking mobile apps with more than 200 million downloads.
Many women have embraced the convenience of tracking menstruation and fertility online. In fact, a study of women in Brisbane, Australia shows that over 70 percent of the women seeking fertility treatment in their sample use a fertility app. Despite their widespread popularity, apps have been criticized for inaccurate prediction of ovulation dates and breaches of privacy. While the apps are marketed as empowering women, the reality is that app-developers are more often aligned with financial motivations, obscuring their intentions by opaque privacy policies and proprietary algorithms.
How accurate are fertility apps?
The accuracy of fertility apps varies widely. While many apps make grand promises about aiding fertility, their actual success rates are rarely published. FACTS facilitated a review of fertility-app effectiveness in 2016, but the digital landscape of offerings is continually changing. While apps do not require FDA approval to legally market themselves as a tool for helping women get pregnant, contraceptive claims are heavily regulated. A 2015 Georgetown study found that out of 30 apps that predicted a fertile window, 24 misclassified fertile days as infertile. This significant finding indicates that the vast majority of apps, though they may claim to enhance understanding of fertility, are likely not using the most up-to-date science on fertility awareness tracking, are without solid grounding in science, and are therefore unreliable for pregnancy prevention.
Some apps simply record the length of a woman’s cycle and suggest an ovulation date based on a rudimentary approach, akin to the oft-maligned calendar or Rhythm Method. These apps function on the outdated belief that all women have a highly regular, 28-day cycle, and always ovulate on day fourteen after their period. One study investigated a sample of these calendar-based apps, and found that they only had a 21 percent probability of predicting the correct ovulation day for any given cycle length.
Clearly, apps with the best track record gather additional information besides just cycle length, incorporating indicators like basal body temperature (BBT), cervical mucus, or even luteinizing hormone (LH) levels into their calculations. The apps based on these hallmarks of Fertility Awareness-Based Methods (FABMs) had high accuracy (defined as the number of predicted fertile days being equal to the number of evidence-based fertile days), but the authors of the above study stress that the majority of the apps were not based on a particular FABM. Many of the most successful apps focus on Sympto-Thermal tracking, although only a few make an effort to teach users to use them correctly. Fertility Friend and apps affiliated with the Couple to Couple League and the Creighton Method stand out as highly accurate and educational apps.
Besides the biological indicators for fertility, many apps request additional information like mood, cravings, pain, and information about intimacy. While these measures may help women and their healthcare providers diagnose underlying medical issues or track conception, not all developers build apps with these goals in mind. Some apps collect this information with the aim of creating a large dataset to mine for menstruation and fertility patterns. More sinister, however, are the apps that simply masquerade as health apps that ultimately aim to gather sensitive—and consequently lucrative—data to sell. As one example of excessive and invasive tracking, Glow tracks intimate information like sexual positions and reports the information in real time to Facebook.
Many apps focus on an algorithmic approach to predicting fertile windows as opposed to tracking additional symptoms. The issue with this approach is that the algorithm is the proprietary information of the company, and thus cannot be evaluated unless the company makes their algorithm available for independent study. Very few apps publish information about the effectiveness of their algorithms. A handful of apps (among them Natural Cycles and Dot) have peer-reviewed studies, but it is possible that many others are simply relying on unsophisticated averages. Some women have reported not even being able to log irregular cycles because the app’s algorithm cannot account for them. While algorithms are often the result of substantial research, they are no substitute for understanding the body’s signs of fertility.
How—and why—are fertility apps sharing my data?
Central to understanding the debate around privacy with fertility apps is understanding the high price of the data of women of reproductive age. Data identifying one pregnant woman is equivalent in value to knowing the age, sex, and location data of 200 other users. The more sensitive the information, the more lucrative. Marketers also value aggregate datasets, say merging data from a fertility app with other demographic information linked to the same email address.
Virtually all apps share data in one form or another. The question is when, who, and how they share it. All apps share data with their internal systems in order to perform the basic app functions. While most apps promise to use current methods to ensure the security of their data, the relentless news about hacks should caution us against trusting the security of any database. Even this tracking within the system can feel violating to some users. For example, some users report anger and frustration at the treatment of data around lost pregnancies, information they would prefer to keep private, but that many apps believe they have a right to record to ensure accurate predictions.
Many apps also share with third parties like social media sites including Facebook and Google Analytics. Even when apps claim not to share with third parties, in reality, app infrastructure often inadvertently shares sensitive data through traffic analysis. An independent study by the watchdog organization Privacy International examines how this happens.
A few apps, such as Dot, Clue, and Natural Cycles prioritize sharing data only for the purposes of scientific research, but they still retain the rights to sell data for financial purposes.
Kindara shares its data with a wearable BBT thermometer—a feature some users might find really helpful.
Data is most often vulnerable when companies fold. Companies view the data users input as a company asset—an insurance policy to profit off of in the case of a marketing collapse.
When questioned about selling data, the CEO of Natural Cycles replied, “We’ve never shared any data for financial purposes.” But that may not always be the case. “I can’t say we’ll never share data, there are no guarantees in life of what will happen,” she added. Indeed, virtually no apps specify what will happen in the case of company collapse. Some will allow you to delete your account, but in the fine print, they often retain the right to the data you put in before the account cancellation.
As health trends favor privatized and personalized health recommendations, many apps share with Apple Health, Fitbit, and other health information aggregating devices. While the products of large tech companies are often secure from external hacks, their good judgment dealing with sensitive data internally is less certain.
Other parties that apps may share data with can include employers and health insurance companies. Ovia’s business model includes partnering with HR departments and selling data about which women are pregnant. While this data is technically anonymized, in reality, there may be so few pregnant women in one office (especially in a small business or department) at the same time that the data is quite easily re-identified. But interestingly, some women who use Ovia say that they like those features, and the ability to access additional features from their HR department.
The country in which the app operates makes a tremendous difference in how private data is managed as privacy restrictions fragment the internet. For example, many EU-based apps are compliant with General Data Protection Requirement (GDPR) guidelines. Broadly, this means that a user’s data will stay private without explicit consent to data sharing.
The aims and goals of women using apps are different, and the wide range of apps means that some apps will be a better fit for some women than others. Understanding the aims and limitations of each of the apps can enable women to at least make an informed choice about their options for family planning and for privacy. While the market of apps is tremendous, below are descriptions of a sample of the different designs, motivations, and science behind a few popular FABM apps that rise to the top from a privacy and data standpoint.
A Sample of Some of the Most Effective, Most Secure Fertility Tracking Apps on the Market
CycleProGoTM
This app works for members of the Couple to Couple League who are using the Sympto-Thermal method for natural family planning. Users can record mensuration, temperature, cervical mucus, and the cervix sign as well as LH tests. The app then uses the CCL method analysis, or Sympto-Thermal rule, to determine fertile and infertile phases.
Important details:
The app comes with a built-in support system. Users can send private messages to their CCL instructors and post questions to public message boards. According to their privacy policy, the CycleProGoTM may share information with third parties for direct marketing purposes in addition to sharing de-identified data for scientific research purposes.
FertilityCareApp
This web-based app offers an electronic way for couples using the Creighton method to track their cycles. The app allows users to track biological signs and share them directly with their practitioner and spouse. FertilityCareApp has a one-time registration fee of $10 with a following monthly subscription of $4.99 a month.
Important details:
The FertilityCareApp is only available through the Saint Paul VI Institute’s Publication Department. The web-based app charts through a HIPAA-compliant server, a privacy distinction reserved for a very small number of apps. As users must be working with a FertilityCare Practitioner to learn the Creighton system, the barrier to using the app is high, but with that comes greater effectiveness and privacy.
FEMM
FEMM connects with a wider network of health providers to offer a comprehensive health program. With robust and useful tracking indicators, women can share their tracking directly with FABM-inclined health providers, and partners. Their privacy plan allows users to delete their own data and to opt out of location tracking. A number of third parties interact with the site to target marketing, although these can be managed by turning off cookies.
Important details:
FEMM has a strong educational component as well as the built-in connection to a wider community of practitioners and medical professionals.
Natural Cycles
The Geneva-based app relies on basal body temperature, LH tests, and a proprietary algorithm maintained by a set of scientists (who, interestingly enough, were hired away from particle accelerator CERN) to predict a fertile window. Natural Cycles stands out among all other apps as the only one with FDA approval, specifically as a contraceptive device. In spite of this distinction, several women have sued for becoming pregnant while using the app to avoid pregnancy, although the staff at Natural Cycles maintains that the pregnancy rates are in line with their published numbers for accuracy.
Natural Cycles’ privacy scores are above average, as the app is fully General Data Protection Regulation-compliant. Unusually, users also have the right to request that their data be deleted (although this would not apply to data that has been aggregated and used in a scientific study.)
Important details:
Natural Cycles is among the few apps to publish peer-reviewed research about its accuracy ratings. An upcoming study uses a data sample to help determine early markers of infertility. Natural Cycles asks consent explicitly for data to be used in scientific studies from all users. For access to their aforementioned proprietary algorithm, Natural Cycles charges a $9.99 monthly subscription fee.
Clue
Berlin-based Clue stands out for possibly the most thorough privacy policy of all the fertility app options. Personal identifying information is stored separately from sensitive health data, an important practice to ensure the privacy of users. Clue maintains two apps, a period tracker app and Clue Birth Control, which received FDA approval in 2021 as a digital contraceptive. Clue tracks the usual suspects like cervical mucus and menstruation, but it also offers options to track health specific information like bowel movements, exercise, pain, and cravings. Many health practitioners hold that this additional information is distracting, but companies like Clue hope to leverage data mining techniques to uncover more information about the factors that drive our cycles.
While the vast majority of apps retain data as an asset, Clue only retains identifiable data long enough to render the services the app provides to its users. In the event that users would like to cancel their account, their data is immediately deleted from the user database.
Clue recently made a database of 11 million de-identified global users available to researchers. By investing in grant funding to scientists, the company hopes to mine the data to better understand patterns in menstruation.
Important details:
The option to use the app without an account and only store data locally on your device sets it apart as a highly private option. Clue also tracks location information through IP addresses. They do not offer an option to use the app without accepting IP tracking.
While all of these apps have plusses and minuses based on one’s needs and preferences, these are apps that, from a data and privacy standpoint, I could recommend as a data scientist.
Stay tuned for more on today’s most popular apps, as we plan to continue covering this ever evolving topic.
This article was last updated on June 28, 2022 to reflect the 2021 FDA approval of Clue Birth Control.
