Menstrual periods may be starting earlier in younger generations, according to new research.
The study was published on Wednesday in the scientific journal JAMA Network Open and based on data from the Apple Women’s Health Study, which involved 71,341 women.
Researchers in the US found that the average age at which girls begin menstruating has decreased from 12.5 years for those born between 1950 and 1969 to 11.9 years for those born between 2000 and 2005.
There has also been an increase in the time it takes for menstrual cycles to become regular after menarche (the first menstrual cycle), with fewer girls achieving regularity within two years and more taking three to four years or never achieving regularity.
The study also found that Asian, Black, Hispanic, and multiracial girls reported earlier average ages of first menstruation compared to girls who were White.
“Early menarche is associated with higher risk of adverse health outcomes, such as cardiovascular disease and cancer,” Zifan Wang, a postdoctoral research fellow at Harvard’s T.H. Chan School of Public Health and corresponding author of the study, said in a statement.
“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”.
Factors leading to earlier periods in young girls
Childhood obesity is a risk factor for early puberty, which could play a role in girls experiencing their first periods earlier.
However, the decrease in the age of first menstruation has been going on before the obesity epidemic, which indicates that other factors could also be influencing this trend.
A 1997 study of some 17,000 girls in the US found that women were starting puberty at younger ages, with studies in other countries also showing earlier onset of puberty in girls.
The Harvard researchers say that other factors besides body weight may contribute to the early onset of puberty in young girls.
A key factor under consideration is the impact of "forever chemicals," which are persistent chemicals used in consumer products.
These endocrine-disrupting chemicals, along with exposure to heavy metals and air pollutants, may contribute to young girls getting their periods earlier than past generations.
