December 20, 2021


Mobile Apps to Assess Menstrual Health: A Summary of Research

By Ciara Sanchez

Editor’s Note: This is a review of research published in 2019 by Symul et al, titled, “Assessment of menstrual health status and evolution through mobile apps for fertility awareness.” Ciara Sanchez wrote it while on the FACTS elective. As technology becomes simpler and more accessible to women who wish to monitor their reproductive health, previous assumptions and long-held facts about the menstrual cycle continue to be challenged and, at times, debunked. As more women learn how to chart their cycles and new research is conducted with the daily data made possible through charting, the sky is the limit as to what can be learned about the female cycle. Such research would expand medical knowledge about reproductive health in unprecedented ways and transform the care of women. 


Mobile apps for menstrual tracking have become much more popular in recent years. They have allowed researchers to evaluate the reliability and tracking frequency of fertility biomarker observations on a massive population-wide scale. The study by Symul et al aimed to identify the suitability of datasets from two of these mobile fertility awareness-method (FAM) tracking apps to assess menstrual health and fertility, and how the findings of these datasets compared to observations from previous smaller-scale studies. The researchers then evaluated whether the precision of these apps allowed for a correct estimate of the timing of ovulation. The study also provides clinicians with information on how FAM tracking apps work and how they might be used in clinical practice. 


The study assessed two de-identified retrospective datasets from two highly rated apps, Sympto and Kindara. Both apps are available for iOS and Android, and all the information from features used in this study was available in the free versions of the apps. The apps studied have some important differences. Sympto is marketed as a natural family planning (NFP) tool that can be used to both achieve and avoid pregnancy; it provides feedback to users based on their observations that point to their most fertile days. On the other hand, Kindara is marketed only to women who wish to achieve pregnancy, and it does not provide feedback to users about their most fertile days. 

Any incomplete cycles, or cycles in which physical signs of fertility were not reported by users, were excluded from the study. The cycles included in the study are known as “standard cycles.” A Hidden Markov Model (HMM) was used to estimate ovulation time. 



User Demographics

The majority of Kindara users are in the United States and trying to achieve pregnancy, while most users of the Sympto app are based in Europe and trying to avoid pregnancy. Most users of both apps are in their late twenties and early thirties, and have a healthy body mass index (BMI).  

Tracking Behavior

To detect changes related to ovulation in a “standard” (~28-day) cycle, a tracking frequency of 8-12 days was needed. Most app users reported their relevant FAM body findings for more than 16 days per standard cycle. Users who also chose to record sexual intercourse during a cycle were more likely to log their findings, with 40% of users reporting their observations every day when seeking pregnancy. 

Kindara allows for more sporadic tracking because it does not provide the user with any feedback about fertile windows. Sporadic or missing data in Sympto was less frequent because it precluded the app’s ability to estimate time of ovulation. 

Fertility Signs

Different FAM biomarker observations reported in the app were compared with data from previous studies to assess whether they remained consistent at the population level. This study showed an average shift of 0.36 °C/0.7 °F in basal body temperature (BBT) at ovulation, and then a decrease of BBT back to normal at the end of the cycle once bleeding or spotting occurred. Both observations are consistent with previous studies with smaller sample sizes. An increase in stretchy cervical mucus (a potential sign of fertility) in the days leading up to ovulation was also observed by the women in this study. 

Estimating Ovulation

Using the HMM to estimate ovulation, the duration and range of the follicular phase were found to be larger than reported in previous studies. Ovulation occurred on days 14 to 15 only 24% of the time. Although the luteal phase duration and range were found to be similar to findings from previous studies, an increase in short luteal phases (10 days or less) was noted in approximately 20% of standard cycles recorded.


Although these apps provide a less precise means of evaluating menstrual health than traditional medical monitoring, such as frequent office visits and hormonal testing, they are more accessible to the population as a whole, requiring only cervical fluid observations and a simple thermometer to monitor basal body temperature. The apps also have simplified free versions that allow patients who may not be able to afford frequent medical visits the chance to monitor their cycles from home.


In a digital age, mobile tracking apps also give patients another way to track their cycles besides paper-based tracking or surveys that rely on memory. In the future, these apps may be utilized more to help users identify menstrual or fertility problems they may be having. 

Editor’s Note: The benefits of tracking menstrual health cannot be overstated, and women can learn how to track their cycles by charting with fertility awareness-based methods (FABMs). These methods include the Sympto-Thermal Method, the Creighton Model, the Billings Ovulation Method, and the Marquette Model, among others, and patients learn how to use each method from a trained instructor. Each woman can choose a method to meet her needs, desires, and family planning goals, which change throughout life. Learn more about the different methods, including their effectiveness rates for family planning, by following the link and scrolling down.


[1]  Symul, L., Wac, K., Hillard, P., & Salathe, M. (2019). Assessment of menstrual health status and evolution through mobile apps for fertility awareness. NPJ digital medicine, 2(1), 64.

About the Author

Ciara Sanchez

Ciara Sanchez wrote this review as a medical student at Georgetown University School of Medicine. She participated in the FACTS selective in fertility awareness during her second year of medical school. After graduation, Ciara plans to specialize in obstetrics and gynecology.

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