If it seems like girls are maturing at younger and younger ages, it’s because they are. In the last few decades we’ve seen rates of early puberty in girls increase dramatically. It’s no longer uncommon to walk into a first-grade classroom and see at least one or two girls who are already showing signs of precocious puberty.
What is early puberty in girls?
Early puberty in girls, or ‘precocious puberty,’ is defined as the emergence of secondary sex characteristics such as breasts, pubic hair or vocal changes in girls 8 or younger. However, given the downward shift we’ve seen in the average age of onset for puberty among girls, this standard might need adjusting. It still could be considered precocious for a girl to begin puberty at age 7 or 8, but it’s certainly not abnormally so anymore.
How common is early puberty in girls?
An ever increasing number of girls are showing signs of entering puberty at age 7 or 8, sometimes younger. A 2010 study of 1,200 girls found that 15% of girls overall (or roughly 1 in every 7) showed signs that they were beginning puberty at age 7. However, rates of precocious puberty varied considerably between ethnic groups: whereas 10% of white girls will begin puberty at age 7 or younger, 15% of Hispanic girls will do the same, and a whopping 23% of Black girls will begin maturing by the same age. By age 8 the percentage of girls entering puberty rises to 18% of white girls, 31% of Hispanics, and 43% of Black girls. (Beil, 2012; NBC Nightly News, 8-9-2010)
What causes early puberty in girls?
Nobody can say definitively what is causing girls to enter puberty sooner, but there are a number of factors—both natural and unnatural ones—hat are linked to precocious puberty in girls:
Genetics & early puberty in girls
To some extent the propensity for early puberty is wrapped up in genetics. If you went through puberty at an early age yourself, there’s a much greater chance your daughter will as well. It’s also true that shorter girls tend to reach sexual maturity at younger ages, since those with more height in their genes spend a few more years growing up before they start filling out. (Falk, 2008, p. 18)
Childhood obesity & precocious puberty in girls
Body weight is a key biological cue that triggers the onset of puberty in girls. When girls reach a body weight of around 80 or 90 pounds, this triggers the body to begin the hormonal changes that start the process of puberty. Thus one of the primary drivers of precocious puberty in girls is our childhood obesity epidemic. A severely obese child may hit this 80 pound threshold at age 5 or 6, triggering the hormonal changes that thrust her into puberty.
Body fat percentage is also involved in the onset of menarche (a girl’s first period). Females are meant to have a certain percentage of body fat, which helps provide the cushion needed to carry a pregnancy to full term. This is why anorexics will lose their period after dropping below a healthy body weight. Normally during puberty, a healthy weight girl will start adding a bit of body fat around her hips and breasts as she starts to fill out, and she’ll get her period a year or two later. But when girls are overweight to begin with, they may experience menarche much sooner, and the length of time between the onset of puberty (i.e., the first appearance of breast buds) and their first period may shorten considerably.
Diet and obesity likely play a significant role in the ethnic differences we see in the onset of puberty. Minority children tend to be poorer, living off poor quality diets consisting of a high percentage of processed foods. Not only does this contribute to obesity, but such a diet is likely to expose them to higher levels of estrogen-mimicking chemicals.
Lack of physical activity is leading to early puberty in girls
Girls who are physically active tend to sexually mature much later than girls who are not as active. Much of this is due to the fact that physically active girls stay thinner and leaner for longer, postponing the onset of puberty. So as girls are becoming less physically active, they’re also entering puberty sooner.
Chemicals may be causing early puberty in girls
Kids today are being exposed to a regular bombardment of man-made chemicals, and this may be tied with childhood obesity for the most influential factor driving up rates of early puberty in girls. Beginning from conception, children are being exposed to thousands of artificial chemicals in the food they eat, the air they breathe, and the things they touch. Many of these chemicals are endocrine disruptors, which means they tinker with the body’s systems regulating hormones. (You can read more about these toxic exposures in our chemicals & toxins area, as well as our book Toxic Environment)
In particular, many commonly used chemicals mimic the female hormone estrogen. Such estrogen mimics can be found virtually everywhere: In plastics, pesticides, flame retardants, detergents, hygiene products, perfume, even air pollution. They are also found in the hormones used to fatten cattle and poultry, which kids can then get by eating these meat products. Some of the main culprits are bisphenol-A, phthalates, polychlorinated biphenyls (once widely used in electrical components), polybrominated biphenyls (contained in certain flame retardants), DDE (a breakdown product of DDT), and dioxins (a common industrial byproduct).
A 2001 study found that girls adopted into the U.S. from overseas who had the highest levels of DDE in their system had high rates of precocious puberty. A 1999 study in the Journal of Pediatrics found that girls exposed to PCBs and boys exposed to DDE in the womb weighed more by age 14, which also resulted in an earlier onset of puberty. (Time, 10-31-2011) One small-scale study of 76 girls in Puerto Rico turned up an especially convincing chemical link: researchers found that 68% of girls who went through puberty early had been highly exposed to phthalates, compared to only 3% of girls developing normally. (Szabo, 4-11-2011)
Girls are being exposed to such chemicals on a regular basis, which is sort of like taking estrogen supplements, and it doesn’t take much to throw this system out of balance. “The endocrine system is so fine-tuned that it depends on hormones in infinitesimally small concentrations, as little as a tenth of a trillionth of a gram, as inconspicuous as one second in 3,169 centuries,” write Shabecoff & Shabecoff. “That means its disruption can take place at infinitesimal exposures.” (2010, p. 30)
This increase in estrogen-like compounds could be tricking the body into starting puberty much sooner than it otherwise would. Chemical exposures are also intertwined with childhood obesity, making it difficult to tease apart the influence of each one. As Dina Fine-Maron states, “the body often stores chemicals in fat cells, (so) an overweight girl is more likely to be exposed to more chemicals—making it difficult to apportion blame between endocrine disruptors and weight gain.” (Fine-Maron, 2015)
A September 2012 study in the Journal of the American Medical Association found that kids with high levels of a common environmental pollutant are more likely to be obese. (Beil, 2012) So the two variables are interconnected with each other. “But with all the estrogen-like elements in the environment it’s virtually impossible to study,” says professor Marcia Herman-Giddens. “There’s no place to find an unexposed population.” (Honolulu Advertiser, 2-17-2008)
Chemical exposure can even have an intergenerational effect. A grandmother’s exposure to DDT was found to be linked to higher body mass index and early first menstruation in granddaughters. (Arnold, 2021) Granddaughters of those in the top third of DDT exposure during pregnancy had 2.6 times the odds of developing an unhealthy BMI, and were more than twice as likely to have started their periods before age 11.
Healthy girls enter puberty sooner
On a slightly more encouraging note, it may be that girls are entering puberty sooner because they’re healthier than girls in previous generations, though I would caution parents that this is likely the least influential factor in comparison to the others I’ve discussed. Reproduction is a sort of biological privilege, something nature reserves for those fit enough and healthy enough to raise offspring. Therefore better nutrition and healthier kids may be knocking several months off the average age at which girls begin to mature.
Medical causes of early puberty in girls
In rare cases, precocious puberty can be caused by problems with the adrenal gland or other medical conditions. These conditions will usually emerge early, so if you have a girl who starts puberty at age 4 or 5, this is likely to have medical origins. If a 6- to 8-year-old is starting puberty absent any of these other factors (i.e., they are physically active and not overweight), this could also have medical origins. In any case, you should probably schedule a well-child checkup with your pediatrician to rule out any medical causes.
Precocious puberty in girls increased during the coronavirus pandemic
Curiously, there was a two- to three-fold increase in precocious puberty diagnoses during the recent coronavirus pandemic. At 22 facilities in the Henon province in China, there was a five-fold increase in 2020 as compared to 2018. (Weiss, 2023) This could be due to a couple of things. It could be that parents, who were now spending more time at home with their children, simply noticed these changes at higher rates than they had before. It could also be that pandemic-related fears caused a spike in health concerns in general, leading more parents to take their kids to the clinic out of concern for their early development.
It’s also possible that pandemic-related behavioral changes added to the pressures contributing to early development in girls. For example, many people stayed indoors, exercised less, and ate more junk food. Mohamad Maghnie, who studies this pandemic spike, found nearly 90% of the young patients seen during the first 15 months of the pandemic had ceased all physical activity. (ibid) If it is true that this increase in early puberty was real (as opposed to merely being an increase in reporting), and that junk food, lack of exercise and obesity contributed to it, it only further illustrates how influential these behavioral habits are when it comes to precocious puberty.
The effects & consequences of early puberty in girls
Early puberty in girls has been linked to slight increases in breast and uterine cancers later in life. This is likely because early puberty begins exposing girls to higher levels of hormones at an earlier stage in their development. Because cancer is a problem of rogue cell mutations with risks that increase over time, earlier development puts girls at slightly higher risk. However, the relative risks are still small, and this isn’t something parents should lose sleep over.
The bigger concerns about girls undergoing early puberty are social, psychological and emotional. Going through puberty at a young age can single girls apart from their peers, leaving them feeling more isolated and out of sorts. They’re more likely to be teased by other students. Girls might be inclined to tease them out of jealousy or merely because they’re different. Boys often tease them as a means of deflecting sexual tension.
Equally problematic is the fact that adults begin treating them differently, too. All adults, but men especially, are likely to hold back on physical affection and adopt a more hands-off attitude, keeping more physical and psychological distance than they would with younger kids. Our sexually neurotic society trains adults to be hypersensitive about the slightest hint of sexual interaction wherein children are concerned. So when girls mature early, many adults don’t know what to do with such a sexually precocious child, and it makes them aloof. Girls pick up on this, noticing the changes in how others treat them. A 7-year-old doesn’t lose her need to be hugged or cuddled just because she has breasts.
Parents need to be sensitive to these issues, doing all they can to treat their girls the same as they always have while helping them make sense of the hassles they’re liable to experience with peers and other people.
Treatment for early puberty in girls
Many anxious parents are wondering, “ls there anything that can be done to prevent or delay early puberty in my daughter?” In most cases, the answer is no. Unless early puberty has some known medical or chemical origin (such as hyperthyroidism or exposure to synthetic hormones), doctors typically find it best just to let nature run her course.
There are puberty blockers and hormonal blockers on the market, typically used with transgender kids, but like all drugs that disrupt the course of normal development, these come with added risks and side effects. So they shouldn’t be used unless there’s compelling reason to do so.
As a general rule, it’s usually better to defer to nature than it is to try to fight against the tide of a girl’s development. You can, however, take steps to try to eliminate any environmental chemical exposures that could be artificially boosting your daughter’s estrogen levels and contributing to precocious puberty. (See our page on Preventing Early Puberty, or get our book Toxic Environment, which explores chemical pollution of all types in greater detail.)
Additional information on precocious puberty in girls
The following pages will explore this topic in greater detail:
* Helping Girls Through early Puberty
* Preventing Early Puberty in Girls
See also: