Menstrual Cycles Starting Earlier and Becoming More Erratic
Researchers say obesity and exposure to environmental chemicals may play a role as girls are starting their periods earlier and experiencing irregular menstrual cycles compared with previous generations.
A new study of 71,341 women adds to growing concerns that the age at which girls begin menstruating is getting younger, and the trend is even more pronounced in certain racial and ethnic groups, The Washington Post reports.
Earlier and More Erratic Periods
The findings also suggest that more young girls and women are experiencing irregular periods for years, a risk factor for a variety of health problems, including cardiovascular disease, metabolic conditions such as diabetes and some cancers.
The data was collected as part of the Apple Women's Health Study, developed by the Harvard T.H. Chan School of Public Health in collaboration with the National Institute of Environmental Health Sciences (NIEHS) and Apple.
Girls Are Starting Their Periods Younger
The study used period-tracking data from iPhones and Apple Watches, as well as surveys to learn more about menstrual cycles, health conditions and gynecological history. The findings may not be representative of the entire U.S. population.
But the findings, published in JAMA Network Open, echo other research, including a study of trends in the age of first period among white and black women in the United States over five decades, based on data from the National Health and Nutrition Examination Survey, a government health trend report.
The new JAMA study found that the average age of first period among Apple users dropped to 11.9 years for those born between 2000 and 2005, compared with 12.5 years for those born between 1950 and 1969.
Participants who self-identified as Asian, non-Hispanic Black or multiracial consistently reported earlier average ages of first period than did white participants.
The researchers say these data are important because Hispanic and Asian populations have been understudied in previous research on age of first period. The study also focuses on a new "biomarker" — the amount of time between a girl's first period and the establishment of regular menstrual cycles.
Risks of Early Periods
"We observed that it takes longer for youth to establish regular menstrual cycles, which is also concerning because irregular menstrual cycles are an important marker for future adverse health outcomes," said study lead author Zifan Wang, a postdoctoral research fellow at Harvard T.H. Chan School of Public Health. "This is a red flag. We need to do earlier counseling and intervention for irregular periods in children and adolescents."
The data also showed that the proportion of girls who started their periods before age 11, or "precocious puberty" before age 9, was higher in recent birth years compared with earlier birth years.
Shruthi Mahalingaiah, a study co-author and assistant professor of environmental, reproductive and women's health at Harvard T.H. Chan School of Public Health, said girls who start their periods at a young age could face more health challenges later in life.
Mahalingaiah emphasized that early life exposures can be signals for future health conditions, which can help inform clinical decision-making about their care. She noted that healthy diet, exercise and adequate sleep are important for girls of all ages.
"I would reiterate the importance of awareness and education, for parents and for health-care providers to be aware of this," she said. "Let's think about what are the modifiable factors that we can potentially act on, to impact not just age of first period but also the time it takes to establish regular cycles."
What's Driving the Trend?
According to the researchers, childhood obesity is a known risk factor for early puberty and appears to be a contributor to the trend. But the earlier age of first period has been seen even before the obesity epidemic, suggesting other factors are at play.
One major concern is "forever chemicals," nearly 15,000 man-made chemicals used in a wide variety of consumer products and found in many food and water sources. These endocrine-disrupting chemicals, as well as heavy metals and air pollutants, may play a role in earlier puberty.
Poor diet, including consumption of sugary drinks, stress, and adverse childhood experiences can also affect the timing of puberty.
Summary
Girls are starting their periods earlier and experiencing more irregular menstrual cycles, which may be linked to obesity, exposure to environmental chemicals, and other factors. The trend is particularly concerning because irregular menstrual cycles are a risk factor for various health problems later in life. Researchers are calling for more awareness and education about the issue.