Kids are starting menstruation earlier, study shows. Here is what that means for their health

By Madeline Holcombe, CNN

(CNN) — Younger generations are getting their first periods earlier, and the length of time it takes to become regular is changing — which could point to later health problems, according to a new study.

“Among individuals born between 1950 and 2005, we found that younger generations were starting their first period (menarche) earlier, and the time it took for their periods to become regular also increased,” said lead study author Dr. Zifan Wang, a postdoctoral research fellow at Harvard University’s T.H. Chan School of Public Health, in an email.

The study, which published Wednesday in JAMA Network Open, looked at data from more than 70,000 participants who filled out surveys as part of the Apple Women’s Health Study, which is a long-term research of menstrual cycles using data from the Apple Health mobile application.

The data was collected digitally, relying on people to self-report the information based on their memories of early menstruation and thus limiting the results, Wang said. But other research has documented the trend in first menstrual cycles starting at earlier ages over time.

In the latest study, researchers compared trends in the ages of first periods and how long it took for menstruation to become regular by age groups, Wang said. They found that the trends were even stronger in people from racial and ethnic minority groups and/or of lower socioeconomic status.

“This is important because early menarche and irregular periods can signal physical and psychosocial problems later in life,” Wang said, “and these trends may contribute to the increase in adverse health outcomes and disparities in the US.”

A vital sign

Menstruation is like a vital sign, said Dr. Eve Feinberg, associate professor of obstetrics and gynecology at Northwestern University’s Feinberg School of Medicine in Chicago. She was not involved in the research.

“You want to make sure that the body is regulated,” Feinberg said. “And when cycles are not regular, it’s generally a sign that something else may be going on.”

Scientists and health care providers already know that early periods and a longer time for cycles to regulate are associated with poor effects on health, including cardiovascular disease and cancer, Wang said.

The longer people have irregular menstrual cycles, the longer they may be exposed to an imbalance between two important hormones: estrogen and progesterone, Feinberg said.

Estrogen signals growth, whereas progesterone signals for that growth to stop, she added. To prevent conditions   such as uterine cancer, you need to have the signals to both start and stop growth.

Theoretically, longer exposures to estrogen without a good balance of progesterone could affect an increase in endometrial cancers and fertility problems in the future, she said.

And an early period itself may pose problems, Feinberg added.

For an 8-year-old to be going through puberty, there is often a disconnect between the age of the child’s mind and body, she said.

Where are these trends coming from?

The next question is: Why are these menstrual trends changing?

Earlier periods might be associated with high body mass index, or BMI, during childhood, Wang said.

“This implies that childhood obesity, which has been increasing in the US, might be contributing to people getting their periods earlier,” Wang added.

The cause could also be other environmental factors such as nutrition or the prevalence of microplastics, Feinberg said, adding that further investigation is needed.

Additional research can help physicians counsel people better about their menstruation and recognize the impact on their patients’ health, said one of the study’s principal investigators, Dr. Shruthi Mahalingaiah, assistant professor of environmental,   reproductive and women’s health at Harvard’s T.H Chan School of Public Health.

Physicians should evaluate children with early periods or a long duration of irregular cycles to make sure there isn’t an underlying problem, Feinberg said.

“Sometimes even using birth control pills at an earlier age to help give earlier exposure to progesterone … may give a little bit more cycle control and may possibly be protective,” she said. “But I think the key is probably really understanding what’s driving this and getting to the root cause.”

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