middle school girls sit on a bench during a sports game
Photo by Jeffrey F Lin on Unsplash

Girls’ periods are starting earlier now than in the past, study confirms

A new study published in JAMA Network Open examined menstrual trends in more than 71,000 US women over the course of 50 years and found that girls today experience earlier and more irregular periods than previous generations.

In short:

  • For girls born between 1950 to 2005, the percentage who experienced their first menstruation before age 11 increased two-fold.
  • These trends were true across all socioeconomic groups and ethnicities, but were more dramatic in non-White individuals and individuals with low socioeconomic status.
  • Weight was a contributing factor, although BMI accounted for just under half the trend towards early periods, and the biggest shift occurred years before the current obesity epidemic.

Key quote:

“These findings suggest that early-life menstrual characteristics have been trending in directions that indicate higher risk of later adverse health outcomes, which may contribute to health disparities.”

Why this matters:

The menstrual cycle is an important indicator of overall health. Early periods are associated with an increased risk of cardiovascular disease, cancers, and premature death, while people who have more irregular periods have a higher risk of metabolic conditions and all-cause mortality. With many environmental toxics linked to earlier puberty, the results of this study highlight the need for more research to identify what role these chemicals play in women’s reproductive development.

Related EHN coverage:

More resources:

Wang, Zifan et al. for JAMA Network Open. May 29, 2024

About the author(s):

Katherine McMahon
Katherine McMahon
Katherine McMahon is a Science Administrative Assistant at Environmental Health Sciences.
Sarah Howard
Sarah Howard
Howard is the Program Manager at the Healthy Environment and Endocrine Disruptor Strategies (HEEDS), a program of Environmental Health Sciences.

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