America's premature puberty phenomenon explained: Girls are starting transition as young as SIX

Girls are hitting puberty younger than ever, thrusting them prematurely into a new world of wild mood swings, physical discomfort, and self-doubt.

The phenomenon is called precocious puberty, which is being detected more and more in the Us. Decades of research point to a trending decline in the age of puberty onset. 

In dozens of countries, the age of puberty in girls has dropped by about three months per decade since the 1970s. Now, it is not out of the realm of possibility to see signs of development in girls as young as six. 

While not inherently dangerous, going through puberty before age eight comes with some sizable health risks for the girl down the line. 

They are more susceptible to developing depression or other psychological conditions in adolescence. And the younger a girl is when she reaches her menarche (her first period), her risk of developing breast cancer later in life rises.

Doctors have not been able to identify a single or even a handful of causes for precocious puberty, though experts told DailyMail.com that some underlying factors include obesity, stress, and genetics

Precocious puberty, which afflicts children all over the world, can also be distressing for the young girl who is suddenly confronted with the changes more suited to a teenager. 

And being the only girl in a class of children who wears a bra or the only one with acne can be extremely alienating. 

Doctors have not been able to identify a single or even a handful of causes for precocious puberty, though experts told DailyMail.com that obesity is likely an underlying factor.

But obesity is not the only factor. Doctors are also eyeing high-stress situations and the omnipresence of microplastics that can disrupt the endocrine system that governs hormones.

The female body typically enters puberty when it hits the 100lb mark, according to Dr Adi Katz, director of Gynecology and director for the Obstetrics and Gynecology residency program at Lenox Hill Hospital.

Pinpointing a ‘healthy’ weight is difficult, though. Genetics and prenatal health both contribute to a girl’s body mass.

The Centers for Disease Control and Prevention has established a range of weights defined as normal. 

A 12-year-old girl’s weight usually falls within the range of 68 and 135 lbs, and the average weight for girls that age is 92 lbs.

Going through puberty before their peers can be extremely alienating for young girls who are suddenly wracked with uncomfortable physical and hormonal changes as well as a bevvy of psychological effects such as anxiety and depression [File image]

‘We are now much heavier than our ancestors; evolutionarily our system thinks that we’re ready at an earlier stage,’ Dr Katz told DailyMail.com.

‘Fat tissue stores hormones and estrogen, so if girls or boys reach a certain weight at an earlier age, they may start their sexual development earlier.

‘On the opposite side, if a person is anorexic, which means they’re not reaching a certain weight, a lot of times the periods will stop altogether and the hormones will kind of shut down because evolutionarily, the body is like there are not enough nutrients, we can’t reproduce.’

As incidences of precocious puberty have become more common since the 1970s, childhood obesity rates have ballooned, rising from 5 percent in 1978 to 18.5 percent in 2016.

There are signs it has gotten even worse.  

For children and adolescents aged two to 19 years in 2017-2020, the prevalence of obesity was 19.7 percent and affected about 14.7 million children and adolescents. 

But while experts have uncovered an association between obesity and early puberty, they cannot pin the cause solely on a person’s weight.

This may be because weight is determined by a whole host of factors, including genetics and prenatal health, not just how often you work out or how diligently you diet.

Obesity can also stem from environmental factors such as income and zip code.

Dr Stephanie Green, a pediatric endocrinologist at Johns Hopkins Children’s Hospital, told DailyMail.com: ‘There are so many confounding factors of obesity because people that are obese are more likely to come from lower socioeconomic status, they’re more likely to have social stressors, they’re more likely to have a family history of metabolic conditions that change your DNA when you’re in utero and lead to generational epigenetic effects.’

‘There are so many confounders there, so when we say obesity, are we talking about just the increased adiposity of a person?

‘Or are we talking about all of the social and metabolic factors and generational epigenetic factors that come with that?’

Obese children tend to have higher levels of a substance called leptin, an integral hormone in weight management, energy expenditure, and appetite.

The hormone is primarily secreted from fat cells in adipose tissue. Because of that, the amount of leptin released is directly related to body fat; the more fat an individual has, the more leptin they will have circulating in their blood.

In early puberty, a girl’s ovaries begin producing estrogen in the phase called gonadarche. Body fat tissue secretes leptin which can then stimulate the secretion of kisspeptin, a protein in the hypothalamus that has been implicated in the regulation of puberty onset. Kisspeptin is also involved in other reproductive factors such as ovarian function, fertility regulation, and lactation.

The activated kisspeptin subsequently activates the Hypothalamic-Pituitary-Gonadal (HPG) Axis, which is primarily responsible for regulating reproductive activity and the release of ovarian hormones, increasing the expression of estrogen and androstenedione in the ovaries.

The average American girl will enter puberty at 11. But that’s not the whole story. In reality, girls can enter puberty healthily as young as 8 but ethnicity plays a big role. Black and Hispanic children typically enter puberty six months earlier than white children. Twelve is considered average for a first period, but that too can change based on

Just as many girls will begin developing later in their adolescence, roughly one percent of girls will start puberty before they turn eight.

As the age of puberty’s onset among American girls continues to drop, researchers are trying to figure out why and whether it can be prevented.

Puberty is marked by sexual development and emotional changes driven by a rise in gonadotropin-releasing hormone (GnRH).

GnRH causes the pituitary gland at the base of the brain to start making and secreting two types of hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In women, they cause the ovaries to make estrogen and progesterone.

Central precocious puberty, the most common type, is caused by premature development of the hypothalamic-pituitary-gonadal axis, which releases pulses of GnRH into a structure at the base of the hypothalamus that serves as a link between the neural and peripheral endocrine systems.

Precocious puberty could potentially increase a woman’s risk of developing health problems later on in life.

A 2010 study published in the Journal of Clinical Endocrinology and Metabolism found that women who got their first period before age 12 faced a 23 percent higher risk of developing heart disease later in life, and a 28 percent higher risk of dying from a heart attack or stroke, compared with those who began menstruating later.

They also had a 25 percent higher risk of dying from cancer, something that previous research suggests is likely attributable to higher overall exposure to estrogen during a woman’s lifetime.

It typically starts with breast development, also known as thelarche. It can occur in girls as young as two and usually precedes the appearance of pubic hair. Thelarche marks the first of five stages of puberty, known as the Tanner Stages.

The Tanner Stages also referred to as Sexual Maturity Ratings (SMR), help health professionals gauge how far a person has proceeded through puberty.

Tanner stage 1 is the start of changes that happen under the surface. For instance, the hypothalamus begins to release gonadotropin-releasing hormones to the pituitary gland, which makes hormones that control other glands in the body.

In stage 2, the changes become more noticeable. Girls with a normal puberty timeline will typically enter this stage between nine and 11. This is when girls will see the first sign of breasts called ‘buds’.

The breast-budding stage is physically harmless. But many girls who go through it have to contend with a society that is all too comfortable sexualizing young girls, and that is likely to foster feelings of anxiety, depression, and self-hate.

At stage three, changes become more noticeable. This is usually when acne appears, hips and thighs widen out, and body hair starts sprouting in more places.

Stage four describes the quintessential signs of puberty that we love to hate – growth spurts, first periods, more pubic hair, and hormones wreaking emotional havoc. Stage five is the culmination of a person’s development, usually around age 15.

Scientists cannot point conclusively to a single driving factor of precocious puberty. Rather, there are several factors driving pubertal development that experts are still trying to understand.

A 2020 report published by Dutch scientists said: ‘In return, estrogen stimulates the expression of the Ob gene in [white adipose tissue], resulting in the synthesis and secretion of leptin.

‘Thus, high levels of leptin promote onset of puberty in girls via secretion of kisspeptin, and estrogen stimulates leptin secretion additionally.’

In addition to obesity, stress can be a key driver of precocious puberty. Family conflict, domestic or sexual abuse, and food insecurity can all jumpstart sexual maturation in girls. A 2007 study published in the journal Child Development reported that ‘stressful family relationships’, as well as a mother’s history of mood disorders both affect puberty onset.

In a separate study published in the Journal of Research on Adolescence in 2012, scientists from Oregon and California found: ‘Collectively, our results confirm previously-reported associations between maltreatment early in life and accelerated pubertal maturation.

‘Physical and sexual abuse each significantly predicted development, with those who experienced childhood sexual abuse exhibiting the earliest timing of development and those who experienced physical abuse exhibiting a more rapid developmental tempo across the duration of the study.’

Stress impacts the brain’s limbic system which controls emotional behaviors such as fear, rage, and anxiety. The limbic system communicates with the hypothalamus, which is in charge of releasing sex hormones. Stressors like living in a household without a father or living in foster care can influence when puberty begins. But the exact mechanisms, such as changes in cortisol levels, remain unknown.

Scientists are also eyeing certain chemicals and pollutants that they believe can jumpstart early puberty, such as Phthalates and Bisphenol A (BPA) which is found in many plastic products and can leach into food. Their presence typically affects low income people who are already predisposed to health conditions related to environmental factors such as obesity.

Dr Green said: here are higher rates, typically of environmental toxins and endocrine disrupters, higher rates of exposure in people that come from lower socioeconomic status for many reasons.’

Environmental toxins, while worth considering, have been deemed a minor contributor to precocious puberty relative to other perceived causes.