By: Kyra Dorsey
For millions of users, period tracking apps promise convenience, clarity and control. But increasing research suggests those predictions may not be as dependable as they seem.
In the past decade, period tracking apps have gained popularity. This is heavily due to the rise of the female technology, or FemTech, industry. The industry focuses specifically on using technology to improve and aid in women’s health.
According to Statista, the term was first coined in 2016 by Ida Tin, the co-founder of Clue, a very popular menstrual tracking app. Statsista also stated that in 2024 the industry had grown to be worth over $60 million.
Health professionals do agree that these tools are helpful, but they definitely have their limitations.
“These apps are a useful tool, but I wouldn’t solely rely on them,” Alyson Drossman, a nurse at a Cornelia, Ga. OB-GYN office, said. “Every female body is different. Outside of using these for general education and reminders, I would always consult your medical physician.”
She also reiterated the point that most of these apps rely on averages and not the individual user. Drossman said that stress, illness, lifestyle changes can all affect the timing of your period. The apps cannot always account for this.
Occupational health student Jordan Harrell shadowed a pelvic health specialist and echoed these concerns.
“Period tracking apps are a valuable tool for women to better understand their symptoms and recognize patterns in their bodies,” Harrell said. “However, as a future practitioner, I recognize these apps are not completely accurate and should be used as supportive guides rather than a sole source of information.”
Period tracking apps do use algorithms to try and predict menstrual cycles, ovulation days, and fertility patterns. But, according to a research article by Lauren Worsfold, a prenatal genetics and fetal medicine expert, the apps are assuming that users undergo a 28-day cycle with ovulation occurring on day 14 and a fertile window between days 10 and 16.
In her research, Worsfold found that many period apps provided conflicting information on period dates, ovulation days, and fertile windows. Worsfold entered participants into 10 different apps and generated 36 cycle predictions from five different participants with varying menstrual patterns.
She found that the apps were often inaccurate. In some cases, ovulation predictions were off by two to nine days. This can lead to uninvited pregnancies, interruptions in family planning, and misleading information about one's health.
Despite all of these limitations, users' experiences widely vary. For some, the apps work quite well.
“It’s been super helpful for me,” Madison Davis, an avid Clue app user. “It tells me when my period is coming and it’s usually spot on.”
Davis has used the app for almost four years and so far she has had very few complications.
“I can always count on my period to come around the end of the month and my app lines up with that,” Davis said.
Others have had very conflicting experiences.
“I stopped using my app because it was so off,” Amanda Chambers, a former user of Clue. ”It predicted my period almost a week early one time and then late the next month.”
Chambers said that she knew she was using the app correctly, so the predictions from the app prompted a visit to the OBGYN.
“My doctor told me that I was fine and that it was ok that my cycle was slightly varying,” Chambers said. “The app made it seem like it was the end of the world.”
This variation in experiences heavily reflects researchers and health professionals' key issue: period tracking apps are not one-size-fits-all tools. In another article, researchers Maria Carmen Punzi and Tamara Thuis explained that the functionality of these apps is attractive but that they come with other risks.
Punzi and Thuis explained that more ethical implications come along with the inaccuracy of these apps. They found that the algorithms used to make predictions are limited in their technological advances and often use data that does not reflect all its users.
This shows that users need to remember that these algorithms that are putting together predictions are not human and they do not have a doctoral degree in women's health. Punzi and Thuis emphasized that this is especially important for vulnerable populations like women of color, immigrants, or people who cannot afford quality health care.
All of this reflects the larger issues within the FemTech industry. It shows that accuracy and accessibility are still evolving. As the technology continues to advance, transparency about the apps’ functions and predictions is vital.
Until then, users are left to navigate a tool that can be helpful, but not always reliable. Timing and accuracy can have real consequences. This leads the researchers and health professionals to agree on one thing: period apps can inform, but they should not be fully trusted.