by Girls in the United States had their first periods earlier over the past five years and took longer to experience regular cycles, a new study has found.
The study, published in JAMA Network Open, found that the trend is particularly significant among participants of Black, Hispanic, Asian and mixed race, and among those who reported lower socioeconomic status.
“This is important because early menarche,” or first period, “and irregular periods can signal physical and psychosocial problems later in life,” said Zifan Wang, a postdoctoral research fellow at the TH Chan School of Public Health. 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 about when they got their first period, when it stopped regularly and for certain demographic information. The researchers then divided the group into five generational brackets.
They found that women born in the oldest bracket, between 1950-1969, got their period at an average age of 12.5 years, compared to 11.9 years for the youngest group, born between 2000-2005.
The study was conducted via an app as part of the Apple Women’s Health Study. This allowed researchers to check back in with a group several 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 to think back many years. Still, the study is likely to inform future research.
As well as a younger average age of menarche, the study found that the rate of people getting their first period early (younger than 11) or very early (younger than nine years) was about double between the older generation and the younger generation. For the oldest group, 8.6% received a period before the age of 11, compared to 15.5% of people in the younger generation. Similarly, 0.6% of people in the older generation had a period before the age of nine, compared to 1.4% in the younger generation.
“We definitely see patients presenting with periods at nine or 10 years of age,” said Dr. Anne-Marie Amies Oelschlager, a pediatric gynecologist at the University of Washington School of Medicine, and chair of the American College of Obstetricians and Gynecologists. Gynecologists (ACOG). ) clinical consensus committee for gynecology.
She continued: “Although this is considered normal, it causes great distress to our patients and their parents. They’re still in primary school in third or fourth grade, and it’s hard to manage periods in third or fourth grade.”
Most importantly, menarche at younger ages may not be pathological. Amies Oelschlager said better sanitation and nutrition are likely at least part of the reason girls are getting periods earlier, in the United States and around the world.
“If someone is showing signs of puberty before the age of eight they should talk to their doctor about it, and if they haven’t had a period by the age of 15 they should talk to their doctor about it,” 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 implications. The onset of puberty meets growth plates, meaning that people who hit puberty early may not reach their genetic maximum height. It can also raise women’s risk of cardiovascular disease and breast cancer.
Early physiological development can also have dramatic social consequences, as 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 behaviors.
Amies Oelschlager said the literature currently suggests that breast development is occurring in young American girls, but more research will be needed to confirm that menarche is occurring on average in girls younger than 12, as a study suggests new JAMA Network Open reveals.
Many factors influence the onset of puberty, but the exact causes of menarche and breast development at younger ages are debated. One hypothesis is that a higher body fat percentage stimulates the pituitary gland to produce puberty hormones. Other research has shown that body mass index is the greatest predictor of early pregnancy. The scientists reason that the higher prevalence of childhood obesity may explain the higher percentage of girls who get early periods.
“What we need to ask is why [body mass index] gone up?” 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 probably part of the answer. But I think it’s another critical piece. our ubiquitous environmental exposure to endocrine-disrupting chemicals.”
Chemicals that affect 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 of them are still uncontrolled despite the warnings of scientists about possible negative effects on human health.
Wang said a wide range of factors need to be taken into account to understand why menarche may be happening to younger girls.
“These factors may include what’s in the environment like chemicals that affect hormones and air pollution, or dietary patterns, stress, and adverse childhood experiences,” she said. “Studying these factors may help us find better ways to stop or slow these trends.”
