What is precocious puberty? Experts explain.

A young girl has a conversation with two people who appear to be her parents.
Precocious puberty is when signs of sexual maturity occur earlier than age 8 in a girl and age 9 in a boy. (Photo: Getty Images)

Every child goes through puberty, but not everyone experiences it at the same time. The average age that a child reaches sexual maturity differs between the genders: Girls experience puberty between 8 and 13 years old and boys experience it between 9 and 14 years old, according to the National Institutes of Health.

However, about 1% of children in the U.S. experience early puberty, otherwise known as precocious puberty.

Dr. Emily Breidbart, a pediatric endocrinologist and assistant professor in the department of pediatrics at NYU Langone Health, tells Yahoo Life that most precocious puberty cases occur a little before age 8 for a girl and around age 9 for a boy. If so, this is a normal variant that doesn’t need to be treated.

“Most of the time, we're reassuring parents in these situations,” says Breidbart. “But there are rare occasions where we need to treat a child who has precocious puberty.”

If you’re a parent and are noticing what seems like the early signs of puberty in your child, you may be concerned about his or her health. Here’s what you need to know about precocious puberty.

What is precocious puberty, and what are the first signs?

Precocious means early or premature. When doctors talk about precocious puberty, they mean any signs of sexual maturity happening earlier than age 8 in a girl and age 9 in a boy. “In a girl, the first signs of true puberty would be breast development, and in a boy, it would be testicular enlargement,” says Breidbart.

Dr. Fadiyla Dopwell Louis-Obike, a developmental-behavioral pediatrician at Pediatrix Developmental Medicine of Dallas, says precocious puberty involves more than one sign, however. “We have to be cautious, because if it’s just one isolated thing, such as having pubic hair early, it doesn’t mean you’ve entered all the stages of puberty,” Louis-Obike tells Yahoo Life.

Another sign of puberty is when children have a noticeable growth spurt. If this happens early, “you’re at risk for not getting as tall as would be expected,” says Louis-Obike. “Since you started puberty sooner, you’ll also stop growing sooner,” she explains.

What causes precocious puberty?

Scientists have still not pinned down a single reason for precocious puberty, and many factors can trigger it. The Endocrine Society says that genetics are the most important factor in the timing of puberty. If you or your family members experienced early or late puberty, the odds of your child experiencing it around the same time are high.

However, the National Organization for Rare Disorders says more recent research has shown that some precocious puberty cases originate in genetic mutations. For example, variations in the KISS1 gene and the KISS1 receptor can cause the hypothalamus to release hormones called gonadotropins, which then signal the start of puberty to the body.

Lifestyle changes may also play a role. A new study shows a spike in early puberty in girls during the onset of the pandemic, which disrupted healthy habits for many. The researchers found that girls diagnosed with precocious puberty were more likely to have higher BMIs, with increased screen time (girls in the study averaged two hours per day on electronic devices) and a significant drop in physical activity (more than 88% stopped exercising) as possible contributing factors.

Is precocious puberty becoming more common?

While precocious puberty is rare, more children nowadays are going through puberty at a younger age. “When you go back and look at the data from the U.S. and Europe, there's been a large decrease in the age that girls have their first period,” Breidbart explains. “The average age was about 17 for menarche in the early 19th century, and then 13 years by the mid-20th century.”

One study of the timing of puberty, conducted between 1977 to 2013, found that the age for breast development had decreased by three months per decade. “We know that breast development is now starting before age 10 in the average girl,” says Breidbart, “and overall, there's been a decrease of about two to three months per decade across the globe over the past 30 to 40 years.”

Although early puberty in boys is not common, studies suggest that the average age of puberty in boys decreased between 1993 to 2008. The researchers attributed the early onset of puberty in boys to an increase in BMI (body mass index).

While type 1 diabetes has previously been associated with delaying puberty, a recent study found that boys and girls with diabetes are also trending toward early puberty onset. Researchers in Germany found that, compared to 20 years ago, both girls and boys with diabetes diagnoses are going through puberty roughly six months earlier. This was especially true for children with lower blood sugar levels, those classed as overweight or those who had diabetes longer.

Are certain groups more likely to go through it?

Both Breidbart and Louis-Obike agree that girls are more likely to experience precocious puberty.

There is also a higher chance of precocious puberty if you belong to a racial or ethnic minority group. Research shows that Black girls were more likely to get their first period at age 12, while white girls had their period five months later. A 2019 study found that Hispanic girls developed pubic hair 12 months earlier and got their first period nine months earlier than previously reported.

In addition, multiple studies — including one conducted in 2021 — suggest that childhood obesity contributes to precocious puberty in both girls and boys.

How can parents help their children adjust to the changes their bodies are going through?

Both experts agree the first and most important thing is to normalize it and to reassure your child that what’s happening to their body is natural.

“Give age-appropriate information,” explains Breidbart. “Even if your child is starting breast development at age 8, it doesn't mean you're having your period at age 8. That usually takes another two to two and a half years.”

She adds: “Giving small doses of information will make them comfortable and not feel they have something to be ashamed of.”

What red flags to look out for might warrant a doctor's visit?

Louis-Obike recommends seeing your child’s pediatrician when a girl before the age of 8 starts growing breasts or if your child has a growth spurt of more than 2 inches a year. “The pediatrician will determine if they need to monitor their growth and determine if endocrinology or therapy needs to be provided to grow appropriately,” she says.

One red flag to look out for is if precocious puberty occurs too early, such as around 4 or 6 years old. While extremely rare, this should be brought to the attention of your child’s pediatrician, to rule out a tumor. “This is not frequent, but precocious puberty can result from specific types of brain tumors that could activate the pituitary gland, which is in charge of the start of puberty,” Breidbart explains.

Your doctor will evaluate the need for treatment on a case-by-case basis. If they believe the onset of puberty has occurred abnormally early, for example, in a 6-year-old, they may prescribe medications, such as GnRH agonists, to suppress puberty.

This article was originally published in April 2023 and has been updated.