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A new study led by researchers at Harvard T.H. Chan School of Public Health has shed light on significant changes in the age at menarche among young women in the United States. Published in JAMA Network Open, the study reveals a decreasing average age at menarche, particularly among racial minorities and those from lower socioeconomic backgrounds. Concurrently, it found an increasing duration for the menstrual cycle to regularize after menarche.
The study draws from the extensive data of the Apple Women’s Health Study, a collaborative effort involving Harvard Chan School, the National Institute of Environmental Health Sciences, and Apple Inc. Over 71,000 participants contributed data, reporting their age at first menstruation, racial identity, socioeconomic status, and other health metrics.
“Understanding these trends is crucial for assessing women’s health across different demographics and environmental contexts,” said co-principal investigator Shruthi Mahalingaiah, highlighting the study’s implications for public health.
Historically, earlier menarche has been linked to various health risks, including cardiovascular disease and certain cancers. The study’s findings indicate a clear trend towards earlier menarche over recent decades. For instance, participants born between 2000 and 2005 reported an average age at menarche of 11.9 years, compared to 12.5 years for those born between 1950 and 1969. Moreover, the prevalence of early and very early menarche has risen notably among younger generations.
Interestingly, the study also revealed that the time taken for menstrual cycles to regularize post-menarche has increased. Factors such as body mass index (BMI) at the age of menarche were identified as potential contributors to these trends, with childhood obesity emerging as a significant risk factor.
“This study underscores the need for further research into the factors influencing early menarche and its health consequences,” noted Zifan Wang, the study’s corresponding author. “Investments in menstrual health research are crucial, particularly as these trends disproportionately affect already marginalized populations.”
While the study provides valuable insights, it acknowledges limitations such as reliance on retrospective self-reporting. Nonetheless, the findings call for continued monitoring and targeted interventions to promote reproductive health among young women in diverse socio-economic settings.
The research was supported by funding from Apple Inc. and the National Institutes of Health, reflecting a collaborative effort to advance understanding in women’s health and reproductive biology.
For more details, the full study will be available in the upcoming issue of JAMA Network Open.
