For decades, girls have been starting menstruation at increasingly younger ages. A new Harvard study has confirmed this trend, showing that the onset of first periods continues to occur progressively earlier. At the same time, it takes longer for menstrual cycles to become regular. This delay raises concerns about potential long-term health effects.

Researchers led by Zifan Wang, PhD, MS, from the Department of Environmental Health at Harvard T.H. Chan School of Public Health, Boston, reported these findings in JAMA Network Open . The study analyzed data from more than 70,000 women born between 1950 and 2005.

Early menarche is linked to a higher risk for obesity, type 2 diabetes, cardiovascular disease, and certain cancers, particularly breast cancer. Childhood obesity is known to pr

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