Girls in the United States have had their first period earlier and earlier over the past 50 years, new study finds | US News

Girls in the United States got their first periods earlier over the past five decades and it took longer to experience regular cycles, according to a new study.

The study, published in JAMA Network Open, found that the trend is particularly pronounced among black, Hispanic, Asian and mixed-race participants, as well as those who reported lower socioeconomic status.

“This is important because early periods,” or first periods, “and irregular periods can signal physical and psychosocial problems later in life,” said Zifan Wang, a postdoctoral researcher at the TH Chan School of Public Health from Harvard University and lead author of the study.

Starting in 2019, researchers from Harvard and the National Institute of Environmental Health Sciences (NIEHS) surveyed more than 71,000 participants born between 1950 and 2005 to find out when they got their first period, when they became regularly and for certain demographic information. The researchers then divided the group into five generational groups.

They found that women born in the oldest age group, between 1950 and 1969, got their period at 12.5 years old on average, compared to 11.9 years for the youngest group, born between 2000 and 2005.

The study was conducted via an app as part of the Apple Women’s Health Study. This allowed researchers to return to a group multiple times, or what researchers call a longitudinal study design.

Although the study was large, it relied on self-reported information – which is generally considered less reliable than sources such as medical or financial records. In some cases, participants would have had to think back decades. Nonetheless, the study will likely provide direction for future research.

In addition to a younger average age of first period, the study found that the rate of people having their first period early (before age 11) or very early (before age 9) approximately doubled between the oldest and oldest generations. the youngest. For the oldest group, 8.6% got their period before age 11, compared to 15.5% of people in the youngest generation. Similarly, 0.6% of people in the oldest generation had their period before the age of nine, compared to 1.4% of the youngest generation.

“We certainly see patients who get their period at nine or 10 years old,” said Dr. Anne-Marie Amies Oelschlager, a pediatric gynecologist at the University of Washington School of Medicine and president of the American College of Obstetricians and Gynecologists (ACOG). ) clinical consensus committee for gynecology.

She continues: “Even though this is considered typical, it is quite distressing for our patients and their parents. They’re still in elementary school in third or fourth grade, and it’s difficult trying to manage periods in third or fourth grade.

It is important to note that the first period at a younger age may not be pathological. Amies Oelschlager said better sanitation and nutrition are likely at least part of the reason girls are getting their periods earlier, both in the United States and around the world.

“If a person shows signs of puberty before the age of eight, they should talk to their doctor, and if they haven’t had their period before the age of 15, they should also talk to their doctor. doctor,” she said. In some cases, very early puberty can be a sign of rare but serious conditions, such as brain tumors.

An early period can have lifelong consequences. The onset of puberty fuses the growth plates, meaning that people who reach puberty early may not reach their maximum genetic height. It can also increase the risk of cardiovascular disease and breast cancer in women.

Early physiological development can also have dramatic social consequences because it does not coincide with early cognitive development. Children who experience early puberty are at increased risk of sexual violence, sexually transmitted infections and early pregnancy.

Early puberty is also associated with an increased risk of depression, anxiety, substance abuse, and suicidal behavior.

Amies Oelschlager said the literature currently suggests that breast development occurs in young American girls, but additional research will be needed to confirm that menarche occurs on average in girls younger than 12, as suggested. the new JAMA Network open study.

Many factors influence the onset of puberty, but the exact reasons for the development of menstruation and breasts at a younger age are debated. One hypothesis is that a higher body fat percentage triggers the pituitary gland to produce puberty hormones. Other research has found that body mass index is the best indicator of when menstruation begins. Scientists believe that a greater prevalence of childhood obesity could explain the higher proportion of girls having early periods.

“What we have to ask is why has (body mass index) increased? ” Dr. Frank Biro, a physician at Cincinnati Children’s Hospital Medical Center, told Scientific American. “Reduced physical activity and a more calorie-dense diet are likely part of the puzzle. But I think another crucial element is our pervasive environmental exposure to endocrine-disrupting chemicals.

Endocrine disruptors from plastics and petrochemical pollution are found in a wide range of consumer goods, including pesticides, building materials, furniture, children’s toys, fabrics and cosmetics. Most remain unregulated despite scientists’ warnings about their potential negative effects on human health.

Wang said a wide range of factors need to be considered to understand why menarche may occur in young girls.

“These factors can include what is in the environment, such as chemicals that affect hormones and air pollution, or eating habits, stress and adverse childhood experiences,” she said. -she declared. “Studying these factors could help us find better ways to stop or slow these trends.”