Human Interest Human Interest News Kids Are Starting Their Periods Earlier, and They Are More Irregular Than They Were in the Past, Study Says Researchers tied to the study said early menstruation could be caused by numerous factors By Nicholas Rice Nicholas Rice Nicholas Rice is a Senior Editor for PEOPLE Magazine. He began working with the brand as an Editorial Intern in early 2020, before later transitioning to a freelance role, and then staff positions soon after. Nicholas writes and edits anywhere between 7 to 9 stories per day on average for PEOPLE, spanning across each vertical the brand covers. People Editorial Guidelines Published on June 1, 2024 11:00AM EDT A stock image of menstrual products. Photo: Getty Kids are starting their periods earlier, and how long it takes to become regular is changing, according to a new study. These findings were published in JAMA Network Open on May 29 using data collected as part of the Apple Women’s Health Study, which was developed by the Harvard T.H. Chan School of Public Health with the National Institute of Environmental Health Sciences (NIEHS) and the tech company. Looking at cycle tracking data submitted by more than 71,000 individuals from iPhones and Apple Watches, the findings discovered that the average age of a first period was 11.9 years among those born between 2000 and 2005, compared to 12.5 years for those born between 1950 and 1969. Those who took part in the study who self-identified as Asian, non-Hispanic Black or multiracial reported earlier average ages of first menstruation than their White counterparts. Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories. A stock image of a female. Peter Dazeley/Getty Images No, Tampax Has Not Changed the Size of Their Tampons “Among individuals born between 1950 and 2005, we found that younger generations were starting their first period earlier, and the time it took for their periods to become regular also increased,” lead study author Dr. Zifan Wang, a postdoctoral research fellow at Harvard University’s T.H. Chan School of Public Health, said in a statement to CNN. Wang added that the findings are "important" because early and irregular periods "can signal physical and psychosocial problems later in life." Wang also noted that "these trends may contribute to the increase in adverse health outcomes and disparities in the U.S.” A stock image of a woman with menstrual cramps. LaylaBird/Getty Images 16 Stars Who Got Real AF About Their Periods, PMS & Everything In Between Researchers tied to the study said early menstruation could be caused by numerous factors. "Notably, obesity is a risk factor for early-onset puberty, and the prevalence of childhood obesity has increased in the U.S., leading to hypotheses on the potential role of obesity in the trends toward earlier menarche," the study said. Researchers also noted that "environmental factors," "dietary patterns, "psychosocial stress" and "adverse childhood experiences" could also play a role.