Fertility Apps: A Deeper Dive

Fertility and menstrual cycle tracking applications are on the rise. Whether the applications are coming from a tech giant like Apple, or a smaller company like Ava Science, companies are increasingly focused on women’s health technology.

While many women are using fertility awareness method apps, few studies demonstrate how accurate the apps are, what information users are tracking and if the data tracked can help them and their gynecologists.

Researchers set out to study the applications at a population level to determine and compare their accuracy in evaluating menstrual health and fertility in a more meaningful way.

The findings, published in npj Digital Medicine, revealed that women seeking pregnancy recorded their Sympto-Thermal measurements every day for up to 40% of their menstrual cycles. The tracking frequency of users is higher than the minimum required to detect changes associated with ovulation. Users logged their observations more if they also logged sexual intercourse.

The research team had two goals:

• To see how and what users voluntarily track on the applications
• To find out if the records allow an accurate detection and estimation of ovulation timing

Researchers tracked more than 30 million days of observations from more than 2.7 million menstrual cycles.

By modeling the data, the researchers found that the average duration and range of the follicular phase — which begins the menstrual cycle and ends at ovulation — were larger than previously reported. Through modeling, the researchers found that only 24% of ovulations occur at days 14 to 15 of the cycle. The duration and range of the end part of the menstrual cycle matched previous studies.

“Our study provides a common ground for users and their doctors to incorporate digital records in their visits, evaluate their own menstrual patterns and compare them with the statistics we report,” said Laura Symul, Ph.D., department of surgery at Stanford School of Medicine.

Symul led a study on 200,000 users of two applications, Sympto and Kindara, which support the Sympto-Thermal Method and facilitate the identification of the fertile and infertile times of a woman’s cycle. These applications take into account recordings of cervical fluid, body temperature at wake-up and other biological signs.

Researchers found that a majority of the women using the applications are around 30 years old with a health body mass index. The users are typically based in North America and Europe. Kindara users are mostly based in the U.S. and are trying to achieve pregnancy, while Sympto users live in Europe and use the app to avoid pregnancy.

“Our study shows that users voluntarily track their menstrual cycle and fertility-related body signs very frequently, and what they track is aligned with what is expected in the vast majority of cases,” said Symul. “While these measurements and observations are noisy and not perfectly regular, they provide valuable information for inferring the underlying hormonal changes and timing of ovulation in a way that is scalable both in time and in a number of participants.”

While Symul and her research team studied how and what users tracked on the apps, Natural Cycles, the first U.S. Food and Drug-approved contraception app, along with industry experts, studied its fertility app to see its success in preventing pregnancies among women from five countries.

Researchers confirmed that it was 93% effective with typical use.

And Fertility Focus, a startup using data and technology to help couples conceive, said its technology can determine the date when ovulation begins with 99% accuracy.

“New technologies, and in particular, self-tracking, are changing the way we perceive our bodies and health,” Symul said.

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