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Why More Kids Are Starting Puberty Earlier Than Ever Before

The age of puberty is dropping, and that pitches children into experiences they are unequipped for. But even after their brains catch up to their bodies, the early mismatch may alter their lives.

Yasu + Junko, used with permission.
Yasu + Junko, used with permission.

At the age of 9, years before her friends—and worse, before her older sister—Emma started developing breasts. Within months, she got her period. She was so ashamed she didn’t tell her parents or any of her friends.

“I felt betrayed by my body,” she says. “It was doing things I didn’t understand.”

Emma’s sister told her that she had breasts because she was fat. The kids at school called Emma “Chubby.” On top of the teasing, she had to secretly grapple with sanitary napkins made for bigger bodies, in bathrooms that didn’t have bins for their disposal or machines that dispensed extras. “They probably have those things now, but they weren’t geared up in the 1980s. I was fairly small, and the pads then felt massive.”

Now 44, she blames her early puberty, in part, for her early years of sex and drug use, and for her anorexia and bulimia. Her self-mutilation, too.

“I hated my body. I think it was all an escape,” Emma says. She had sex for the first time when she was 11, with a boy her age. Thereafter it was mostly with boys a few years older.

“I felt these urges I wanted to have sex, but I had no real knowledge about it. It was a purely instinctual thing,” she says. “I didn’t know what a period was when I got it, and no one sat down and talked to me about it. I was operating from a place of profound ignorance.”

The anorexia and bulimia started as ways to backpedal all the changes in her body. “I didn’t want to nourish this foul and ridiculous body,” she recalls. Her breasts indeed shrank, but her periods kept coming. Then starvation delivered a whole other set of rewards—she loved the head rush. “You get this high, this detachment from yourself, your life, and your emotions. It was that escape that I sought,” she says. And along the way, she also turned to marijuana and speed—more ways to flee the feelings of self-loathing. She began cutting herself too, perhaps to deflect the emotional pain she had no words for.

“I had a very nice mother and a nice father, I went to a good school, and I had no hardship or abuse in my life, but I felt as if I were living through hell. I had terrible PMT [premenstrual tension]. Those hormonal shifts made me incomprehensibly miserable.”

Puberty—a biological transformation that not only switches on the reproductive organs but also drives changes in sleep cycles, facial structure, voice, fat distribution, body hair, and height—can be a pretty rough ride for anyone. Right at the age when young people want to be like everyone else, their bodies lurch forward in ways far out of their control. Under the best of circumstances, puberty stimulates emotional distress: It fractures self-concept, fosters social uncertainty, and creates new vulnerabilities to clinical anxiety and depression, especially, but not exclusively, among girls.

For those pitched into it early, the journey to adulthood can be terrifying and tumultuous—not least because the hormonal shifts activate subcortical neural reward circuits for adult sexual behavior and beef up the emotion-intense amygdala while the more prudent prefrontal cortex is in no rush to maturity. They also heighten sensitivity to feedback from peers and reactivity to everything and everyone around them. It’s hard to handle all the biological, social, and emotional upheaval when most of your brain is still in grade school.

Yasu + Junko, used with permission.
Yasu + Junko, used with permission.

A Burden for Girls

Developmental psychologist Jane Mendle, head of the adolescent transitions lab at Cornell University, reports that girls who get their periods early are especially subject to distress and more likely than others to suffer from panic attacks, suicidality, body dissatisfaction, substance abuse, and depression that extends into adulthood. They are more likely to be singled out for sexual harassment at school. They are also at risk for antisocial behavior in their teen years.

Their sexualized looks can land them in circumstances that are complicated and confusing and put them at risk for sexual victimization and partner violence. “Early maturers are forced to grapple with new stressors before they may be emotionally or cognitively ready to do so, and with fewer resources than their peers who reach the same developmental milestones at a later chronological age,” Mendle recently wrote in Developmental Review.

Psychologists refer to the mismatch between physical and emotional development on one hand and cognitive development on the other as “maturational disparity.” Early-maturing boys are not exempt from social and emotional problems that can follow from having an adult-like body with the problem-solving skills of a child, Mendle notes, but the data are simply not as robust for males as for females.

For both, sweeping changes in biology, appearance, self-perception, behavior, and emotion lay a foundation for later life. Nevertheless, says Mendle, “experiences of early-maturing girls seem to channel them into life paths from which it is difficult to deviate.”

Puberty brings changes across virtually every domain of a kid’s life, she adds. “After infancy, this is the vastest, as well as the quickest, transformation we ever experience. But unlike infancy, we are cognizant of the changes of puberty as they occur. This conscious awareness underlies a lot of puberty’s association with psychological distress.”

It took Emma four decades and many stabs at psychotherapy to tame the self-loathing set off by premature puberty. “I spent a lot of my life wanting to be out of my own head, out of my body,” she says. “I just didn’t want to be in me.”

From Aristotle to Bach

The goal of puberty is to prepare the body to reproduce. Traditionally, it is the gateway to adolescence, a period of psychological, intellectual, and social growth that readies children for the social roles and independence of adulthood. But increasingly, puberty starts in middle childhood.

On average, puberty today begins around age 10 or 11 in girls (11–12 in boys) and ends between 15 and 17, although some bodies speed through it in a year while others take a more gradual course. The American Academy of Pediatrics considers puberty early, or precocious, if it occurs before age 8 in girls, age 9 in boys. Budding breasts are among the first signs of puberty. Nevertheless, the major landmark for girls is menarche, the onset of menstruation, usually about two years after puberty begins. The onset of puberty in boys is less dramatic.

The first reference to puberty dates to Aristotle. “When twice seven years old, in most cases the male begins to engender seed, and at the same time hair appears upon the pubes. At the same time in the female the breasts swell.”

The average age of menarche, most experts agree, hit an all-time high of 17 during the mid-1800s. By the 1960s, it had declined to about the age of 12. Researchers believe that 12 may be the more normal number, and that the rise was an aberration due to poor nutrition and the rapid spread of infections during the British industrial revolution.

The body’s first obligation is to support its own energy needs for everyday functioning. Only then can it countenance reproduction. Inadequate diet as well as disease or other significant stress on the system can deter the brain’s hypothalamus from issuing the start signal of puberty. Resources are reserved for staying alive.

In a 1997 report in the journal Pediatrics, a team of University of North Carolina researchers found that the start of puberty may have declined by about six months to two years from the 1960s low. Among 17,077 girls between the ages of 3 and 13, breast buds and pubic hair started, on average, by age 10 among white girls and by 8.9 years among African-American girls. There was little change in menarche: 12.3 years among white girls and 12.1 among black girls.

Similar declines have been noted in age of puberty onset in Europe and among boys. A 2010 study of 4,000 boys, by Marcia Herman-Giddens, the leading researcher of the 1997 study, measured testicular enlargement. By that measure, boys were entering puberty around age 10, about six months to two years earlier than previously reported.

Another indication that the onset of puberty is earlier comes not from scientists but from choirmasters. In 2012, the director of the famed St. Thomas’s Boys Choir in Leipzig, Germany—Johann Sebastian Bach once served as music director—discovered that the voices of boy sopranos started to crack at age 13, compared with 14 or 15 in the 1990s. (Records dating to the 1700s suggested that boys’ voices during Bach’s tenure, 1723 to 1750, changed at 17 or 18.) For the choir, the declining age of puberty is an expensive and exhausting proposition. It means constantly selecting, schooling, and voice-training ever-younger boys in order to maintain a corps of sopranos.

Yasu + Junko, used with permission.
Yasu + Junko, used with permission.

Not by Genes Alone

Sexual Maturation consists of two distinct but overlapping processes—gonadarche and adrenarche. Puberty kicks off when the hypothalamus (a brain gland within the limbic system that controls emotion, memory, and arousal) starts generating gonadotropin-releasing hormone. It, in turn, prompts the pituitary to spew out two hormones—luteinizing hormone and follicle-stimulating hormone—that trigger the ovaries to produce estrogen and progesterone and the testes to release testosterone. The sex hormones prompt breast enlargement and then menstruation in girls, testicular and penis enlargement and sperm production in boys.

The other signs of a maturing body—underarm and pubic hair, pimples, and body odor—are due to hormones released not from the brain or sex organs but from the adrenal glands that cap the kidneys. Adrenarche typically occurs six months to a few years before puberty. All too often, says pediatric endocrinologist Alan Rogol of the University of Virginia, parents see pubic hair on their young child and worry that it is the start of precocious puberty. Most of the time it is not.

Puberty is also linked to the release of growth hormone, and early puberty brings with it early growth of the body’s long bones. Girls who go through puberty early may tower over their second-grade classmates but they wind up becoming short adults—menarche halts long-bone growth. And because hormones do not act in isolation, growth hormone does more than stimulate stature: It affects the way the body burns calories, secretes insulin, and utilizes glucose.

In the web of hormonal interconnections, estrogen also stimulates the growth of receptors for oxytocin, a hormone tied to social affiliation. Girls going through puberty early may suddenly become more needy of friendships, in ways that are out of step with their peers.

But no one knows what sets puberty off in the first place. Behavioral genetics studies show that somewhere between 50 and 80 percent of puberty timing is controlled by genes. Biologically driven as it is, puberty’s timing can be influenced by an array of environmental factors.

Environmental Triggers

Scientists have long known that food availability and nutritional status influence reproductive capability, including pubertal timing. Just as undernutrition can delay puberty, overnutrition, as measured by body mass index, can speed its onset. Studies show that overweight girls are more likely to enter puberty early than are underweight peers. In 1965, about 5 percent of kids ages 6 to 11 were obese. In 2008, nearly 20 percent were.

Over the past few decades, concern has also risen that chemicals in plastics, lotions, and other personal products mimic estrogen and may speed puberty. Because the chemicals are ubiquitous, exposure is thought to be widespread, including among pregnant women, where the disruptors could affect the developing fetal brain. Growing children may also be especially vulnerable, exposed through such everyday products as toothpaste and f lame-resistant pajamas. The main culprits are phthalates, found in scented products, such as deodorants, soaps, and shampoos; parabens, used as preservatives in cosmetics; triclosan, an antibacterial agent recently banned from most soaps but still in some toothpaste; and benzophenone-3, a sunscreen in some lotions and lipsticks.

“The hypothalamus is acutely sensitive to estrogen; if it sees estrogen before it’s supposed to, that can trigger puberty before it’s supposed to,” says biologist Heather Patisaul of North Carolina State University. “We know that estrogenic chemicals can trigger early puberty in animals; it makes sense biologically that the same would be true in humans.” So far the major evidence is only correlational. Investigators at the University of California, Berkeley, have correlated levels of metabolites of several suspect chemicals in the urine of pregnant women and that of their children at age 9 with the development of early puberty in girls (but not boys).

Yasu + Junko, used with permission.
Yasu + Junko, used with permission.

Family Matters

In 1991, developmental psychologist Jay Belsky stirred the world of child development by declaring that the timing of puberty could be affected by psychosocial stressors as well as by physical stressors such as starvation and disease. Now at the University of California, Davis, Belsky, after reviewing his own studies, and those of others, through an evolutionary lens, reported that adverse early life experiences and harsh parental environments can accelerate the life course by provoking early puberty.

“It’s an uncanny finding,” Belsky told The New York Times. “Who would have thought a 7-year-old going through the stress of parental fights and divorce would have earlier puberty as a result? We propose that the time of puberty is regulated and influenced to some extent by these earlier experiences, rather than being a fixed biological given.” It’s not a conscious strategy, Belsky pointed out. But a body that senses dangers ahead will rush the reproductive cycle.

While children are learning to read and write, they are also gathering information about their family environment, gaining “an understanding of the availability and predictability of resources in the environment, of the trustworthiness of others, and of the enduringness of close interpersonal relationships, all of which will affect how the developing person apportions reproductive effort,” Belsky reported in Child Development. The early-rearing information, operating through multiple neurobiological pathways, stimulates maturation of the axis linking the hypothalamus and the gonads.

Puberty encompasses a paradox, Cornell’s Mendle explains. While it is universal, it is also individualized. “Earlier onset of puberty occurs disproportionately among adolescents whose environments are marked by such adversities as child maltreatment, poverty, unstable family structure, harsh or unsupportive parenting, and exposure to partner violence.” Further, she notes, everyone varies in the way they experience puberty—not to mention how they deal with the consequences.

An Appraisal of Childhood

Stimulated by the Belsky findings, psychologists have been trying to figure out just how environmental conditions affect the biology of puberty. Their collective research reflects what is known as “life history theory.” As articulated by one of its major architects, Bruce Ellis, a professor of developmental psychology at the University of Utah, life history theory seeks to “explain the timing of reproductive development and events across the lifespan in terms of evolved strategies for distributing finite metabolic resources between the competing demands” of growth, maintenance, and production of offspring, he says in Psychological Bulletin.

Analyzing studies conducted in the U.S. and New Zealand between 1999 and 2012, Ellis found that father absence during early childhood was linked to accelerated onset of puberty.
Fathers have unique effects on their daughters’ sexual development: The absence of father investment in a daughter may speed puberty. In later analyses of data Ellis also found that girls who experienced warm and supportive parenting and biological father presence in the early preschool years had later than average pubertal development. At the same time, substantial evidence indicates that severe psychosocial stress can suppress reproductive development.

Environmental influences can work in an array of ways, Ellis now believes, and he has put forth an “integrated life history theory” to explain both the slowing of pubertal onset and the acceleration of it. He calls it “child development theory.” Both highly stressed and well-protected children develop heightened biological sensitivity to the family context in which they develop. In early childhood, neurobiological circuits are relatively plastic; the information that children gather about their environment attunes the stress response circuits to their circumstances.

“Physiological stress response systems, including the autonomic nervous system and the hypothalamic-pituitary-adrenal axis, operate as mechanisms of conditional adaptation, with a key role in regulating the development of individual life history strategies,” Ellis explains in the 2019 Annual Review of Psychology.

Children adaptively calibrate the length of childhood to match the information they’re getting about their family environment. “The effects appear to be continuous,” says Ellis. “Warm, supportive childhood conditions are associated with later puberty; harsh—especially violent or threatening—
conditions are associated with somewhat earlier puberty; and moderate stress is associated with more moderate acceleration of puberty. In some extraordinary circumstances, psychosocial stress can shut down growth.”

He now sees early puberty as less about rushing into reproduction than about attenuating a distressing childhood. The moderately high levels of stress resulting from unpredictability in family life serve to bring childhood to a quick close, leading to early puberty. The safety of stable and warm family environments fosters the continuation of childhood, allowing children maximum time for acquiring behavioral and cognitive competencies. In short, says Ellis, “pubertal timing [is] a bioassay of chronic childhood conditions.”

Yasu + Junko, used with permission.
Yasu + Junko, used with permission.

Help from Home

Perhaps the genetic dice were loaded in Emma’s case. After years of fertility treatments, she gave birth to a daughter who also showed signs of early puberty. “She was three years and four months when I noticed pubic hair,” Emma reports. A thorough physical exam ruled out brain tumors. Emma says she was “terrified” for her daughter. She didn’t want her to also inherit propensities toward anorexia and self-abuse.

Emma remembers acutely that her parents never explained anything to her; they just sent her for therapy. Intent on protecting her daughter, she created channels of communication: “I told her, ‘Your body is trying to grow up too early, so we’re giving you medicine until you are big enough.’”

The medicine is Lupron, a hormone blocker that delays puberty and further development of the menstrual cycle, but it does not reverse any changes that have already occurred, such as pubic hair and breast enlargement. The treatment, by injection, can be painful. It can cause depression, weight gain, and headaches.

Still, Emma’s greatest concern is keeping her child informed. “It’s important for her to know what’s going on. Children absorb information at a level that they can. We create what is to be ashamed of. Children have no preconceptions of what’s normal or abnormal.”

“It’s one thing to go through puberty relatively early; it’s another thing to go through puberty relatively early in relation to others you are interacting with,” says pediatrician Ronald Dahl, director of the Institute of Human Development at the University of California, Berkeley. A child going through puberty needs a lot of support; a child going through puberty without a peer group needs even more emotional support.

“They need scaffolding,” says Dahl. “You are priming children to develop autonomy and a strong sense of self, just the way you provide scaffolding to a building when it needs extra support—and remove it when it’s stable.”

How Parents Can Help Kids Navigate Early Puberty


Kids with precocious puberty feel as if their life is being threatened. They don’t look like anyone else. They don’t know they’re going to be okay. When a child begins puberty early, try to normalize the situation as much as possible, advises Meredith Russell, a nurse practitioner in pediatric endocrinology at the University of California, San Francisco. Help children recognize that they’ve reached a universal milestone, just ahead of schedule. The goal is to relieve stress and make the experience less scary.


Open an age-appropriate discussion. Share information in a way younger kids can understand: Be honest and concrete. If children believe their parents are hiding information from them, they are likely to imagine horrible things. Avoid making it seem that there are secrets, or that they must not tell anyone about their condition.


Let children express their fears; ask them how they are coping. Children may find their own ways of dealing, which can have dangerous consequences physically and emotionally. If a young child is distressed, consider reaching out to a psychologist who can work with young children through role-playing.

Create a circle of Support:

With your child’s permission, it may help to reach out to a trusting teacher who can keep a close eye on any subtle activity that may be distressing your child at school. Professionals can help children come up with suitable responses to peers and adults, a coping skill they are unlikely to have at a young age. Parents and children can also reduce their isolation by finding support groups online.

Restore a Sense of Control:

The goal is to provide a child with coping mechanisms to avert social anxiety or bullying, which can affect school performance.

Recognize Sensitive Moments:

As much as a child may try to cope at school, activities that involve locker rooms can be tough. Finding new after-school activities, farther from home and with older children, may help a child feel like less of an outcast.

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