A recent study published in JAMA Network Open in May 2024
Revealed that children are not only starting their periods at younger ages but also taking longer for their cycles to become regular.
The data for this study came from the Apple Women’s Health Study.
A collaboration involving the Harvard T.H. Chan School of Public Health, the National Institute of Environmental Health Sciences (NIEHS), and Apple.
Researchers analyzed menstrual cycle data from 71,341 participants using iPhones and Apple Watches
They found that girls born between 2000 and 2005 began menstruating at an average age of 11.9 years.
Compared to 12.5 years for those born between 1950 and 1969. This generational shift suggests changes in the factors influencing puberty timing.
The study also highlighted racial and socioeconomic disparities
Participants identifying as Asian, non-Hispanic Black, or multiracial reported experiencing their first period earlier than White participants.
Additionally, younger generations not only started menstruating earlier but also took longer to establish regular cycles. According to lead researcher Dr. Zifan Wang, these trends could signal potential long-term health risks, including irregular periods being linked to later health complications.
A key finding was the association between early menstruation and body weight. Overweight children are at greater risk of starting puberty early, and the rising rates of childhood obesity in the U.S. may partly explain the declining age of menarche. Other potential influences include environmental factors, dietary habits, stress, and adverse childhood experiences, which merit further exploration.
The study emphasized the public health implications of early menarche and irregular cycles. Trends toward earlier menstruation and delayed cycle regularity were particularly pronounced among racial and ethnic minority groups and individuals from lower socioeconomic backgrounds.
An exploratory analysis revealed that body mass index (BMI) accounted for a significant portion of the decline in the average age of menarche.
These findings underscore the need to address the factors driving these trends, as they contribute to adverse health outcomes and growing disparities in the U.S.