2024 Newsletter: Celebrating Five Years of the Apple Women’s Health Study

Dear Participants,  
 
As we celebrate another remarkable year of the Apple Women’s Health Study, we also mark an important milestone: five years into the study. It feels like we just began this ambitious project to fill the gap in menstrual health research. We want to thank each of you—more than 120,000 participants—for your continued involvement and contributions. While our research team is made up of skilled researchers, the true heart of this work is your active participation. Thank you for being part of this study. 

As we continue, we want to revolutionize women’s health research—to inform health, wellness, and improve the quality of health across the lifespan. This year, we were thrilled to publish multiple research papers. One important paper was Menarche and Time to Cycle Regularity among Individuals Born between 1950 and 2005 in the US. This paper got national attention. It showed that people born more recently are getting their first periods at earlier and earlier ages. It was your participation that made this groundbreaking work possible. Thank you. 

Looking ahead, our team is excited to explore new areas of health research. We ask for your continued engagement and support as we enter this next phase of discovery together. 

Thank you for another incredible year. We look forward to what the future holds! 

Kind regards, 

Shruthi Mahalingaiah MD, MS 
Russ Hauser MD, MPH, ScD

Brent Coull PhD 
Michelle Williams SM, ScD 

A Year in Review

This year marked a big milestone for the Apple Women’s Health Study. We completed our fifth year and made discoveries that have improved how we understand menstrual health.

We are excited to share what we learned! 

One of our most important papers was Menarche and Time to Cycle Regularity Among Individuals Born Between 1950 and 2005 in the US. Our team reviewed data from over 71,000 individuals born between 1950 and 2005. We found that people are getting their periods (menarche) earlier and taking longer to have regular menstrual cycles. This was more noticeable for non-Hispanic Black, Asian, and multi-racial individuals, and those from lower-income backgrounds. Higher body mass index (BMI) at the onset of menarche also played a role in these patterns.

In the paper, Seasonal Variations of Menstrual Cycle Length in a Large, US-based Digital Cohort, we analyzed over 125,000 menstrual cycles. We found that cycles were generally shorter between May and December. This was more noticeable for younger participants and people with polycystic ovary syndrome (PCOS).

Another important publication was Irregular Cycles, Ovulatory Disorders, and Cardiometabolic Conditions in a US-based Digital Cohort. If a participant had irregular cycles, or it took a long time for their periods to be regular, they had a higher chance of heart and metabolic conditions. Things like BMI and physical activity play an important role in these health outcomes.

There are many hormones that control the menstrual cycle, puberty, fertility and physical characteristics. In another paper, Signs of Potential Androgen Excess Across the Lifespan in a US-Based Digital Cohort Study, we looked at participants’ symptoms. Some symptoms may be caused by high levels of androgens (for example, testosterone). These symptoms, like extra hair growth on parts of body, or acne, were compared based on things like age and health status. 

During pregnancy many things change. We published Trends in Sensor-Based Health Metrics During and After Pregnancy: Descriptive Data from the Apple Women’s Health Study. This work shows how physiology, like heart rate, and behaviors, like step count, change during and after pregnancy. 

We had another paper focused on pregnancy, Early Life Menstrual Characteristics and Gestational Diabetes in a Large US Cohort. Here we looked at the age a participant got their first period, and when their periods became regular. We found that if periods started at a younger age, or if it took longer to have regular cycles, that this could be a marker for gestational diabetes (pregnancy diabetes). 

And finally, our study update, Understanding Exercise Patterns and Heart Rate Throughout Pregnancy, looked at changes in exercise habits and heart rate during and after pregnancy. The findings show how pregnancy, which places a lot of stress on the heart, may change a person’s vital signs at rest or while walking. 

Sharing the research globally

Our team has shared our research around the world and continues to learn from leading experts in the field. This past year our research team traveled to San Francisco, Chile, and Singapore to share results. Presenting at these conferences allows us to introduce other researchers, scientists, and doctors to our work. 

Learnings from the Apple Women’s Health Study were presented at:

• American College of Obstetricians and Gynecologists Annual Clinical and Scientific Meetings – San Francisco, CA
• American Society of Reproductive Medicine Conference – Denver, CO
• Endocrine Society Conference – Boston, MA
• The Festival of Genomics and Biodata – Boston, MA
• Annual Conference of International Society for Environmental Epidemiology – Santiago, Chile
• The Society for Pediatric and Perinatal Epidemiologic Research Annual Meeting – Austin, TX
• The Annual Meeting of the Society of Reproductive Investigation – Vancouver, Canada
• Women’s Health Conference 2024 – Singapore

The future

We continue to see more people enrolling in the AWHS and sharing important data. At our five-year anniversary there are over 120,000 participants. An additional 8,700 joined the study this year! Each participant makes this research possible. Each participant is important. You are just as much a part of these discoveries as our research team.

As we look ahead to next year, we are excited to deepen our understanding of menstrual health research. With your support, we hope to explore menopause, the types of personal care products participants are using, and how menstrual cycle lengths change through the reproductive lifespan.

The Apple Women’s Health Study team thanks its participants for their continued contributions to public health research. For more information see the FAQ page.

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