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May 31, 2024

Girls are starting their periods earlier in life, and that may lead to adverse health issues later

Researchers say increased rates of obesity may be partly driving the trend, which is particularly prevalent among minority groups and children in lower-income households.

Children's Health Menstruation
Menstrual Cycle Study Swen Pförtner/Sipa USA

Girls are getting their first periods at younger ages and it is taking longer for their menstrual cycles to regulate, new research confirms. Early menarche – beginning menstruation before age 11 – is linked to adverse health issues later in life.

Girls are getting their periods earlier and it is taking longer for their menstrual cycles to regulate – trends that are putting more girls at risk of health problems later in life. 

The average age of menarche, the onset of the first menstrual period, has been decreasing nationwide, especially for girls in minority groups and of lower socioeconomic status, according to a study published Wednesday in JAMA Network Open. Researchers also found that the average time it is taking for a girl's menstrual cycle to regulate is lengthening.

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The findings are significant because early menarche is associated with a variety of health risks, including an increased prevalence of obesity, insulin resistance and high cholesterol in adulthood, culminating in higher risks of cardiovascular diseases. Early menarche is also linked to psychosocial problems such as anxiety, depression, substance use and suicidal behavior in adolescents.

"Continuing to investigate early menarche and its drivers is critical," said study author Zifan Wang, a postdoctoral research fellow at Harvard's public health school. "Early menarche is associated with higher risk of adverse health outcomes, such as cardiovascular disease and cancer. To address these health concerns – which our findings suggest may begin to impact more people, with disproportionate impact on already disadvantaged populations – we need much more investment in menstrual health research."

The study is the latest publication from the Apple Women's Health Study, a long-term study of women's health. Previous research has indicated that menstrual cycles were starting earlier, but these studies lacked sufficient data to show trends in specific racial or socioeconomic groups or to determine average time to develop menstrual cycle regularity.

More than 70,000 women born between 1950 and 2005 answered surveys about their menstrual cycles. Defining early menarche as younger than 11 and very early menarche as younger than 9, researchers found that the average age of menarche for participants born from 1950-1969 was 12.5 years, and the rates of early and very early menarche were 8.6% and 0.6%, respectively. Among participants born from 2000-2005, the average age of menarche was 11.9 years, and the rates of early and very early menarche were 15.5% and 1.4%, respectively.

The percentage of participants whose periods regularized within two years of onset decreased from 76% to 56% across the two groups.

The findings were more pronounced for Black, Hispanic and Asian women than for white women and for women who self-reported as being of lower socioeconomic status.

Researchers found that childhood obesity, which disproportionately affects Black and Hispanic children and children in lower income families could partly explain the decline in age of menarche. But environmental factors, psychological stress and adverse childhood experiences might also be at play, researchers said.

A limitation of the study was that it relied heavily on self-reporting.

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