Advancing female health

Science and research at Flo

On a global level, female health lacks research. That’s why it underpins everything we do at Flo. Together with our scientific advisory board and collaborators, we’re working to build a better future for female health through innovative research studies.

Our science team is committed to finding new ways to support groundbreaking app features and addressing the gaps in female health science.

working to advance female health

research participants

The latest research and studies from Flo

How we improve female health through research: An interview with Flo’s director of science

When do perimenopause symptoms start?

Female sexual well-being: Flo’s latest research

Behind the Scenes: Meet the Science Team Making Flo a Trusted Health App

Health literacy: Everything you need to know

How are your cycle and your sex drive linked?

Flo's scientific advisory board

Meet the experts we partner with for our research.

Dr. Jennifer Payne

Dr. Lubna Pal

Sarah E. Hill, PhD

Sarah Garfinkel, PhD

Jan Multmeier, PhD

Liisa Hantsoo, PhD

See all advisors

Flo's scientists

Our science team is made up of the people behind our groundbreaking research studies. They’re committed to bringing the latest evidence-based science to female health and the world.

Liudmila Zhaunova, PhD

Adam Cunningham, PhD

Aidan Wickham, PhD

Yella Hewings-Martin, PhD

Yihan Xu

Publications

2025

Perimenopause symptoms, severity, and healthcare seeking in women in the US

Peer-reviewed paper in npj Women’s Health

Key findings:

We conducted a cross-sectional survey of 4,432 women aged 30 and over in the US to understand healthcare seeking for perimenopause, symptoms and symptom burden, and the impact of age on these.
Healthcare seeking for perimenopause was highest among women aged 56 and over (51.5%), but 30% of those visiting a doctor about symptoms were under 46.
Total symptom burden was highest in women aged 51 to 55 and lowest in women aged 30 to 35.
However, significant proportions of women in all age groups reported moderate to severe symptom burden including 55.4% of women aged 30 to 35 and 64.3% of women aged 36 to 40.
The types of symptoms that women most likely experience varied by age with psychological and mood symptoms more prevalent in women aged 41 to 45 and vasomotor and other physical symptoms more prevalent in women aged 51 to 55.

Female sexual response among Flo app users in the United States

Peer-reviewed paper in npj Women’s Health

Key findings:

Sexual problems are commonplace and impact an estimated 41% of females in the United States.
In a survey of 2,392 Flo app users in the US, we used the scientifically validated female sexual function index 6 (FSFI-6) to measure female sexual response.
Those who were using Flo’s Trying To Conceive mode and those who were logging sex events more often had higher FSFI-6 scores, indicating better sexual response.
Conversely, women with a body mass index below 18 (underweight) and those who had at least one chronic health condition queried in the survey had low FSFI-6 scores.
Study participants who were 35 and over reported higher orgasm frequency, less pain during sex, and lower satisfaction with their overall sex life than women under 35, although the overall FSFI-6 scores were comparable.

2024

Exploring Self-Reported Symptoms for Developing and Evaluating Digital Symptom Checkers for Polycystic Ovarian Syndrome, Endometriosis, and Uterine Fibroids: Exploratory Survey Study

Peer-reviewed paper in JMIR Formative Research

Key findings:

The most prevalent self-reported symptoms were fatigue, feeling anxious, high BMI for PCOS, very regular lower abdominal pain, fatigue, and referred lower back pain for endometriosis, and fatigue, bloating, and changing sanitary protection often for uterine fibroids.
The most predictive self-reported symptoms were symptoms of anovulation, amenorrhea, and hyperandrogenism for PCOS and symptoms related to abdominal pain and the effect pain has on life, bleeding, and fertility complications for endometriosis and uterine fibroids.
Symptom checker accuracy was 78% for PCOS, 73% for endometriosis, and 75% for uterine fibroids.

Longitudinal associations between women’s cycle characteristics and sexual motivation using Flo cycle tracking data

Peer-reviewed paper in Scientific Reports

Key findings:

We used data from 16,327 Flo app users to examine the association between menstrual cycle characteristics and sexual motivation.
Shorter, more regular cycles predicted small increases in sexual motivation when comparing between women.
Shorter cycles predicted greater sexual motivation that month and the next month when comparing within the same women from month to month.
This was also linked with more frequent logging of fatigue, insomnia, and food cravings.
But changes in sexual motivation did not reliably precede changes in cycle length.
Our results suggest that menstrual cycles characteristics and sexual motivation may covary together in ways that reflect changing investments in reproduction.

Chronicling menstrual cycle patterns across the reproductive lifespan with real world data

Peer-reviewed paper in Scientific Reports

Key findings:

The length of the menstrual cycle and menstrual cycle related symptoms show clear age associated patterns.
With increasing age, cycles get shorter and more variable until age 40-44.
From this age onwards, periods become longer and more variable, indicating transition toward menopause.
The proportion of individuals with irregular cycles was highest in participants aged 51-55 (44.7%), and lowest in the 36-40 age group (28.3%).
Frequency of logging of cramps and acne is lower in older participants, while logs of headache, backache, stress and insomnia are higher.

Efficacy of the Flo app in improving health literacy, menstrual and general health, and wellbeing in women: a pilot randomized controlled trial

Peer-reviewed paper in JMIR mHealth and uHealth

Key findings:

Using Flo for three months improved primary outcomes of health literacy, menstrual health awareness, health and wellbeing.
It also improved secondary outcomes of feelings of control and
management over health, communication about health, menstrual cycle stigma, and fear of unplanned pregnancies.
For users with PMS/PMDD, it additionally improves symptom burden and absenteeism from work, and education.

Methods for Evaluating the Efficacy and Effectiveness of Direct-to-Consumer Mobile Health Apps: A Scoping Review

Peer-reviewed paper in BMC Digital Health

Key findings:

There is a lack of standardized tools and regulations for mobile health apps.
We evaluated studies that investigated efficacy and effectiveness of mHealth apps, including companies at varied financing stages, with a mix of start-ups (16%), scale-ups (29%), and public companies (39%). A portion of apps were developed by universities or government groups (16%).
Most apps (94%) fall into the wellness category, with diet and nutrition, exercise and fitness, mental health, and sleep as the top subcategories.
Researchers use a variety of study designs to evaluate apps, the most prevalent being randomized controlled trials (RCT).
Lack of diversity in study populations should be addressed to ensure inclusivity and equity.

The Effect of Stress on Reported Pain in Users of a Mobile Health App during the Russia-Ukraine Conflict

Peer-reviewed paper in npj Mental Health Research

Key findings:

Women in Ukraine reported increased stress after the Russian-Ukranian conflict started. At the same time, they reported pain less often.
After the conflict started, women in Ukraine who reported stress were less likely to report pain. This finding is consistent with the phenomenon of stress-induced analgesia.

2023

Assessment of a Digital Symptom Checker Tool's Accuracy in Suggesting Reproductive Health Conditions: Clinical Vignettes Study

Peer-reviewed paper in JMIR mHealth and uHealth

Key findings:

Single-condition symptom checkers have high levels of agreement with general practitioner classification for endometriosis, uterine fibroids, and PCOS.
Sensitivity for the symptom checkers was 81.8% for endometriosis, 84.6% for uterine fibroids, and 100% for PCOS.
Specificity was 84.6% for endometriosis, 81.8% for uterine fibroids, and 75% for PCOS.
Positive predictive value was reported as 81.8% for endometriosis, 84.6% for uterine fibroids, 80% for PCOS; and negative predictive value was reported as 84.6% for endometriosis, 81.8% for uterine fibroids, and 100% for PCOS.
Our paper establishes a robust framework for vignette validation of symptom checkers.

Characterization of Self-reported Improvements in Knowledge and Health Among Users of Flo Period Tracking App: Cross-sectional Survey
Peer-reviewed paper in JMIR mHealth and uHealth

Key findings

Most study participants reported improvements in menstrual cycle (88.98%) and pregnancy (84.7%) knowledge from Flo app use.
Most of the Flo users (73.5%) who used the app to track their pregnancy believe that Flo helped them get pregnant!
The key components of Flo app that helped users improve their cycle knowledge and health are the predictions about periods, fertile days, and ovulation, as well as symptom tracking. Meanwhile, reading articles and watching videos helped users learn more about pregnancy.
The strongest improvements in knowledge and health were observed in Premium, frequent, and long-term Flo app users.

2022

Menstrual Cycle-Associated Symptoms and Workplace Productivity in US Employees: A Cross-Sectional Survey of Users of The Flo Mobile Phone App
Peer-reviewed paper in Digital Health

University of Virginia

Key findings

45.2% of users reported missing, on average, 5.8 days of work due to their cycle.
48.4% do not feel supported by their manager, and 94.6% report no workplace benefit regarding their menstrual cycle.
The Flo app helped 88.7% of users to feel prepared and more aware of their bodies and 77.6% to feel supported.

Global Menstrual Cycle Symptomatology

Preprint

Key findings

Cramps were the most common premenstrual symptom.
Somatic, gastrointestinal, and negative mood symptoms were most common in the late luteal phase and least common in the midfollicular phase.
Negative mood symptoms decreased throughout the follicular phase, while positive mood symptoms were most common in the late follicular phase.

Rates of Self-Reported Postpartum Depressive Symptoms in the United States Before and After the Start of the COVID-19 Pandemic

Peer-reviewed paper in Journal of Psychiatric Research

Johns Hopkins School of Medicine and University of Virginia

Key findings

Throughout the COVID-19 pandemic, an increase in postpartum depression was found in 36 states of the USA.
The increase in postpartum depressive symptoms was greater in the states with fewer deaths from COVID-19 and in the ones where unemployment rates for women were lower in 2020.

Risk Factors Associated with Postpartum Depressive Symptoms: A Multinational Study

Peer-reviewed paper in Journal of Affective Disorders

Johns Hopkins University

Key findings

First-time mothers were more likely to report depressive symptoms than mothers with more children.
Depressive symptoms were the highest among young mothers (18-24 years).
Mothers of twins reported a higher burden of depressive symptoms than mothers of one child.

Premenstrual Symptoms Across the Lifespan in an International Sample: Data From a Mobile Application

Peer-reviewed paper in Archives of Women’s Mental Health

Key findings

The most common PMS symptoms were food cravings (85.28%), mood swings or anxiety (64.18%), and fatigue (57.3%).
Physical premenstrual symptoms increased with age.
Premenstrual symptoms regarding anxiety and mood remained similar with age.
How much premenstrual symptoms interfere with daily functioning every cycle varies across different countries.

2021

Characterization of Polycystic Ovary Syndrome Among Flo App Users Around the World

Peer-reviewed paper in Reproductive Biology and Endocrinology

Northwestern University

Key findings

The most common symptoms of polycystic ovary syndrome (PCOS) vary across different countries.
Bloating was the most frequently reported symptom among women with PCOS.
Women were at least 3 times more likely to have a PCOS diagnosis if they bloat or have high blood cholesterol and glucose.
A PCOS diagnosis is more common in women with a higher BMI.

2020

Relationship Between BMI and PCOS Symptoms Among Flo App Users in the United States

Poster presentations

Northwestern University

Key findings

PCOS is more common as BMI increases.
Having hirsutism increases the probability of PCOS by more than 3 times.
The most common symptoms of PCOS vary across different BMI categories.

Menstrual Cycle Length and Patterns in a Global Cohort of Women Using a Mobile Phone App: Retrospective Cohort Study

Peer-reviewed paper in Journal of Medical Internet Research

Adelaide University

Key findings

More than 90% of women typically have a cycle length of 21 to 35 days.
Less than half — only 40% — of women have a usual cycle length of 27 to 29 days.
Length and variation of the cycle are influenced more by women’s age than the body mass index.
Less variation and shorter cycles were found in women older than 40.

Want to work with us?

We’re always looking for scientists, institutions, universities, and research groups (including corporate research groups) with in-depth subject matter expertise and proven contributions to global health and well-being.

Please get in touch if you would like to collaborate with us.

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