Apple Women’s Health Study shows promise in predicting serious conditions

Preliminary findings from the Apple Women’s Health Study show that menstrual cycle tracking on iPhone and Apple Watch has the potential to detect risk factors for serious health conditions.

The team behind the study said that this is an under-researched area, and the data from 50,000 study participants is advancing the science in this field …

The Apple Women’s Health Study

Apple first announced the study back in 2019, alongside the then-new Apple Research app.

In partnership with Harvard T.H. Chan School of Public Health and the NIH’s National Institute of Environmental Health Sciences (NIEHS), Apple has created the first long-term study of this scale focused on menstrual cycles and gynecological conditions. This study will inform screening and risk assessment of conditions like polycystic ovary syndrome (PCOS), infertility, osteoporosis, pregnancy and menopausal transition.

It uses data pulled from the Cycle Tracking app introduced with watchOS 6, and made more reliable with the new temperature-sensing capabilities in the Apple Watch Series 8 and Ultra.

The team shared its first early results back in 2021, based on 10,000 participants. It said that the study had enabled medical researchers to understand the prevalence of symptoms associated with different stages of the menstrual cycle.

The most frequently tracked symptoms were abdominal cramps, bloating, and tiredness, all of which were experienced by more than 60 percent of participants who logged symptoms. More than half of the participants who logged symptoms reported acne and headaches. Some less widely recognized symptoms, like diarrhea and sleep changes, were tracked by 37 percent of participants logging symptoms.

Latest findings

The new preliminary findings enabled researchers to identify the incidence of more serious conditions that can be associated with irregular cycles.

12 percent of participants reported a PCOS diagnosis. Participants with PCOS had more than four times the risk of endometrial hyperplasia (precancer of the uterus) and more than 2.5 times the risk of uterine cancer.

5.7 percent of participants reported their cycles taking five or more years to reach cycle regularity after their first period. Participants in that group had more than twice the risk of endometrial hyperplasia and more than 3.5 times the risk of uterine cancer, compared to those who reported their cycles took less than one year to reach regularity.

Apple recently highlighted the polycystic ovarian syndrome (PCOS) incidence.

The hope is that the data will highlight the importance of people reporting cycle irregularities to their doctor, so that tests can be performed to enable earlier detection of these conditions.

Anyone in the US who has ever menstruated is eligible to participate in the study through the Research app. All health data collected is of course completely anonymized.