Why More and More Girls Are Hitting Puberty Early

In the wake of Covid, data is emerging from several countries that girls are hitting puberty earlier (in fact, much earlier) than they used to. Thirty years ago the “…average age of onset of puberty in girls—defined in most medical literature as thelarche, when breast tissue begins to develop—was about eleven years old. Menarche, or first period, was thought to happen around age thirteen. Only a small percentage of girls had started puberty by the age of eight, much less started menstruating. But, by the two-thousands, new research had found that eighteen per cent of white girls, thirty-one per cent of Hispanic girls, and forty-three per cent of Black girls had entered thelarche by age eight, according to a study published in 2010. Often, these girls were taller than most of their peers and showed other signs of accelerated physical maturation, such as pubic hair and underarm odor. Thelarche typically presages the onset of menstruation by two to three years, meaning that some of these girls would have to deal with the mess and discomfort of a monthly period before they’d finished elementary school….
Then, during the coronavirus pandemic, pediatric endocrinologists saw a new surge of referrals for girls with early puberty. Recent retrospective studies from Germany and Turkey show that the number of these referrals doubled or even tripled during the lockdown periods of 2020 (this at a time when many families may have been avoiding non-emergency doctor’s visits for fear of covid-19). A paper published in August in the journal Frontiers in Pediatrics, which analyzed data from South Korea’s national statistics portal, found that the number of children diagnosed with precocious puberty almost doubled between 2016 and 2021, with a sharp post-2020 spike. The rise in early puberty “is a phenomenon that is occurring all over the world,” Frank M. Biro, the former director of the adolescent-medicine division at Cincinnati Children’s Hospital Medical Center, told me. (Although there has also been a rise among boys, girls experiencing early puberty still vastly outnumber them.)”
So what is going on? Why has the age at which girls enter puberty dropped by 3 years? The article in the New Yorker offers a variety of hypothesis: “Researchers and physicians hypothesized about possible causes for the increase in early puberty, such as increasing rates of obesity; greater exposure to endocrine-disrupting chemicals found in food, plastics, and personal-care products; and stressful or abusive home environments….
When researchers investigated possible reasons that more girls were entering puberty sooner, they focussed on three main factors. One was stress—they hypothesized that higher cortisol levels might contribute to the premature activation of the pituitary and adrenal glands….A second factor was exposure to endocrine-disrupting chemicals, which can scramble or mimic the body’s naturally occurring hormones….Speculation about the main causes of early puberty eventually coalesced around a third factor, one that was easier to isolate: body-mass index. Average B.M.I. and obesity rates in girls had risen somewhat in tandem with rates of early puberty. Some research suggested as well that both elevated cortisol levels and high exposure to E.D.C.s are associated with higher B.M.I. Meanwhile, structural racism and failures of environmental justice have ensured that Black and brown girls are more vulnerable to all three of these factors than are white or Asian girls, who tend to enter puberty later….
A crucial, perhaps overlooked link between early puberty and the youth mental-health crisis is sleep. Marlon Goering, a doctoral student in psychology at the University of Alabama at Birmingham, studies the relationship between pubertal timing and behavioral challenges in young people. He told me that melatonin, the sleep-regulating hormone that the brain produces in response to darkness, may have contributed to the pandemic-era jump in early puberty. During the lockdowns, many children got less sleep and more irregular sleep, and they spent vastly more time in front of the blue light of screens, which inhibited their ability to secrete melatonin. A drop in melatonin can contribute to symptoms of anxiety and depression; it also activates an increase in a protein called kisspeptin, which is another of the trigger hormones for puberty.”
The surge in early puberty is bad news because there are a host of adverse health consequences associated with it: “…early puberty is associated with a daunting list of adverse physical and psychological outcomes: various studies have suggested that early-maturing girls are at greater risk for developing obesity, breast cancer, eating disorders, depression, and a range of behavioral issues. Especially in the midst of what is increasingly understood to be a post-covid youth mental-health crisis, the startling new uptick in early puberty is troubling to some physicians and parents.”

If you want to read our other published material, please visit https://marcellus.in/blog/

Note: The above material is neither investment research, nor financial advice. Marcellus does not seek payment for or business from this publication in any shape or form. The information provided is intended for educational purposes only. Marcellus Investment Managers is regulated by the Securities and Exchange Board of India (SEBI) and is also an FME (Non-Retail) with the International Financial Services Centres Authority (IFSCA) as a provider of Portfolio Management Services. Additionally, Marcellus is also registered with US Securities and Exchange Commission (“US SEC”) as an Investment Advisor.