Recent research indicates a curious trend among females regarding the onset of menstruation. Girls born in the 2000s start their periods approximately six months earlier than previous generations.
A study published in JAMA Network Open (May, 2024) reveals that the average age of menarche—the first menstrual period—has decreased from 12.5 years in the 1950s and 60s to 11.9 years for those born between 2000 and 2005.
The study analyzed data from over 71,000 females in the United States using the Apple Research App on their smartphones.
Because age at menarche is a pivotal indicator of health, this shift is alarming.
Researchers also found that the prevalence of early menarche (when it occurs before age 11) increased from 8.6% in the 1950s and 1960s to 15.5% in the early 2000s.
And, the percentage of girls starting their period “very early”—before age 9—increased from 0.6% to 1.4%.
But wait, there’s more… Periods now take longer to become regular.
In the 50s and 60s, 76% of females had a regular cycle within 2 years. It has dropped to 56% in those born in the early 2000s.
While the changes are being seen in every demographic, they are especially pronounced in non-white girls and those from lower socioeconomic backgrounds.
Lifelong Consequences
But what difference does it really make when a girl begins her period?
The timing of menarche is linked to a higher risk of disease later in life.
For example, research indicates that abnormal timing of menstruation—whether it starts early or late—can be linked to a higher risk of adverse cardiovascular outcomes, such as heart attack, stroke, and hospitalization due to heart failure. Early onset of menstruation is also associated with an increased risk of developing certain cancers, including endometrial and breast cancer.
On a behavioral level, girls who experience early menarche are at higher risk of becoming pregnant or contracting a sexually transmitted infection (STI) before age 18. Likewise, their risk of miscarriage also increases throughout life.
Girls who take longer to settle into regular menstrual cycles may face reduced fertility and a higher risk of chronic health conditions, including diabetes, high blood pressure, and elevated cholesterol.
They also have a higher rate of all-cause mortality.
In other words, deviations from the norm come with substantially increased risk.
Why is this happening?
According to the study’s authors, almost half of this change in timing — 46% — is due to the meteoric rise of childhood obesity in the U.S.
Higher body fat in young girls is associated with earlier periods.
Body fat, or “adipose tissue,” is metabolically active and produces hormones, including sex hormones, which can influence the age of menarche.
In an editorial published alongside the current study, Lauren C. Houghton, PhD, assistant professor of epidemiology at Columbia University, wrote:
“In general, countries with a mean age of menarche above 12 years reflect populations facing undernutrition and higher infectious disease burden; countries with ages younger than 12 years reflect populations with over-nutrition and higher risk for chronic diseases.”
Although the rising weight of children in the U.S. is a significant factor, it does not provide a complete explanation. It also does not clarify why girls from lower socioeconomic backgrounds, as well as Black, Asian, and people of other or mixed races, are experiencing even greater shifts in the age of menarche.
Interestingly, the study’s authors explain that previous research “showed that the biggest decrease in age at menarche occurred before the obesity epidemic in the U.S.”
They outlined some other possible explanations.
The researchers believe that metals, endocrine-disrupting chemicals, and air pollutants may be affecting the age of menarche. Studies have linked early menarche to exposure to phthalates and triclosan, especially in overweight or obese individuals. It is speculated that certain minority groups face higher exposure to these pollutants, potentially explaining the observed racial disparities.
Diet is a key component, too.
Previous studies revealed that young girls who drink caffeinated and artificially sweetened soft drinks are more likely to get their period earlier. This result remained significant even after the researchers adjusted their analysis to account for BMI.
The sugar in soda triggers insulin release, which can affect sex hormone levels. Although scientists do not understand the precise mechanism, soda’s rise in popularity over recent decades makes it another likely culprit.
Alongside obesity, pollution, and diet, stress and adverse childhood events (ACEs) may play supporting roles, but there is currently less evidence to support these factors.
What can be done?
How can parents and young girls navigate this?
You can start by teaching your children to eat a balanced diet, avoid fast foods, and encourage regular exercise and stress management as part of their routine.
Regardless of when the changes occur, communication is crucial.
Make sure the girls in your life feel seen, heard, and valued. Let them know that they aren’t going crazy when all the hormones start revving up.
Help them understand what they are going through. Educate them on hormones and what their body is doing. Have age-appropriate conversations about what they may be feeling and experiencing. And most importantly, do not leave any room for shame or guilt. This is what our bodies are designed to do. It should be cause for celebration, not shame!
This is supposed to be a sacred, beautiful time in a girl’s life. But it seems as though it’s getting more difficult to explain and express how beautiful and sacred our precious girls are. If you have a (grand)daughter, sister, niece, aunt, or friend who needs to be reminded of just how intricately and wonderfully designed she is, take the time to remind them of how beautiful they are.
When these conversations happen, be sure to listen to her. That will tell you a lot about what’s going on inside.
Also, it’s a great excuse to eat some dark chocolate.
Sources:
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2819141
https://www.healthline.com/healthy/what-is-menarche
https://www.ahajournals.org/doi/10.1161/JAHA.119.012406
https://pubmed.ncbi.nlm.nih.gov/33820799/
https://pubmed.ncbi.nlm.nih.gov/7386450/
https://www.sciencedirect.com/science/article/abs/pii/S1570677X18302429
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2819142
https://pmc.ncbi.nlm.nih.gov/articles/PMC6603611/
https://pmc.ncbi.nlm.nih.gov/articles/PMC4325672/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10426011/
https://pmc.ncbi.nlm.nih.gov/articles/PMC6720214/