The age at which girls get their first period has fallen over the past 50 years, research has shown.
Harvard researchers found that girls now ages 19 to 24 got their first period when they were 11, on average, compared to women now ages 55 to 74, who had an average age of 12 when They had their first period.
Over fifty years, the number of girls under nine years of age beginning to menstruate has also increased.
The trend could be due to the rise in childhood obesity, the researchers said. Previous research has linked the phenomenon to the consumption of junk food, chemical pollution and certain pollutants.
Menarche, which is the first time girls get their period, usually occurs between ages 11 and 15, according to the Cleveland Clinic.
Harvard researchers found that girls now ages 19 to 24 got their first period when they were 11.9 years old, on average, compared to women now ages 55 to 74, who had an average age of 12. .5 years when they had their first period.
Researchers studied 71,341 people as part of the Apple Women’s Health Study, which used cycle tracking data from iPhones and Apple Watches, as well as surveys to gain additional information about menstrual cycles.
They also found that Asian and non-Hispanic black participants were more likely to report earlier menstruation.
Other studies have suggested that this is unlikely to be due to genetic variations and may be due to “other environmental or contextual factors that may, through racism, affect different pathways, leading to earlier menarche,” the researchers said.
Menarche, which is the medical name for girls’ first periods, traditionally occurs between ages 11 and 15, according to the Cleveland Clinic.
The girls in the study also reported that their menstrual cycle took longer to become regular.
The number of participants whose cycle became regular within two years of starting their periods has decreased over the past five decades.
The percentage of participants who had their period before age 11 increased over the years
The number of participants reporting regularity within two years of starting their periods has decreased over the past five decades.
Zifan Wang, lead author of the study, said Washington Post It was worrying that girls seemed to take longer to achieve regular menstrual cycles.
‘This is also very worrying because irregular cycles are an important indicator of adverse health events in the future. It alarms us.
“We need to provide more counseling and early intervention on irregular cycles among children and adolescents,” Dr. Wang said.
Irregular periods have been linked to various diseases, including coronary heart disease, type 2 diabetes, and rheumatoid arthritis.
The data also showed that the proportion of girls with very early periods (before age nine) was higher in the most recent birth group compared to the earliest birth group.
The decrease in the age of first period could be due to the increase in childhood obesity, the researchers said, as it is a risk factor for earlier puberty.
Overweight children have higher levels of sex hormones and levels of leptin, a hormone produced by fat cells, which can accelerate puberty.
While childhood obesity may play a role, the decline in first period age that began before the obesity epidemic suggested that other factors might be involved.
A big concern is permanent chemicals: a group of about 15,000 man-made chemicals found in everything from consumer products to food and water.
These can disrupt hormones and potentially bring forward puberty.
Things like a poor diet, including lots of sugary foods, stress, and adverse childhood experiences can also affect the starting point of puberty.
Other research has shown that very early puberty increased during the pandemic, which may be due to the stress it caused in the lives of young children.
The study was published in the journal JAMA Network.