Early Puberty: Causes and Consequences

For a parent, discovering that your child is entering puberty early can be alarming. Why is it happening? Can your child really handle the effects -- both physical and psychological?

Many kids who have early puberty don't need treatment. In those who do, treatment usually works well in halting the process. Here are some basic facts about the causes of early puberty and the ways it might affect your child.

What Is Early Puberty?

Puberty starts on average in girls between ages 8 and13 and in boys between ages 9 and 14.

Doctors diagnose early puberty when this normal process starts early and continues to progress through growth spurts and bone maturation, usually for reasons we don't understand. Girls who show significant signs of puberty and its progression before age 7 and boys before age 9 are considered precocious. About 1 out of 5,000 children are affected.

There are two types of precocious puberty, central and peripheral.

  • Central precocious puberty is the more common type. The process is identical to normal puberty, but happens early. The pituitary gland is prompted to produce hormones, called gonadotropins. These hormones in turn stimulate the testicles or ovaries to make other hormones, testosterone or estrogen. It's these sex hormones that cause the changes of puberty, like breast development in girls.
  • Peripheral precocious puberty or precocious pseudo-puberty is a different condition. It's also rarer. The hormones estrogen and testosterone trigger the symptoms. But the brain and pituitary gland are not involved. It's usually a local problem with the ovaries, testicles, adrenal gland, or a severely underactive thyroid gland.

There are other conditions that might look like early puberty to parents -- and sometimes even to pediatricians -- but aren't.

  • Premature thelarche is early breast development at a young age. It often appears in girls who are just a few years old. While troubling for parents, it resolves on its own and is not true early puberty. It does not require treatment but should be evaluated.
  • Premature pubarche is the early development of some pubic or underarm hair at an early age. It can be caused by premature adrenarche, when the adrenal glands start releasing hormones early. Again, while it might seem alarming, it's generally not a problem and not an early sign of puberty. However, because this may represent the first sign of an abnormal and excess release of adrenal hormones, it should be evaluated.

Many experts say that, on average, puberty is starting earlier in the U.S. than it did in the past. The average age of menstruation has stayed roughly the same. Yet studies suggest that early signs -- like breast development -- are happening a year earlier than they did decades ago.

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Early Puberty Signs

The signs of early puberty and puberty are usually the same. It's the timing that's different. Signs include:

In girls

  • Breast development (which is often the first sign)
  • Menstruation (typically not until two to three years after the earlier symptoms start)

In boys

  • Growth of the testicles, penis, and scrotum
  • A deepening voice (usually late signs of puberty)

Growth spurts are another sign of early puberty in both boys and girls.

 

Causes of Central Precocious Puberty

In most cases, experts don't know what causes central precocious puberty, particularly in girls. 

Sometimes, central precocious puberty is triggered by a medical problem. Underlying causes are more common in boys and children under age 6, especially if puberty is advancing rapidly. They can include:

  • Tumors and other growths, which are often benign
  • Brain injury, either from surgery or a blow to the head, that affects hormonal balances
  • Inflammation of the brain, sometimes from an infection

That probably looks like a worrisome list. Just remember that only in a small number of cases in boys is central precocious puberty caused by a medical problem. In girls, it is extremely rare for a medical problem to be the cause.

Early Puberty: Related Factors

While they aren't necessarily causes, a number of factors seem to be related to early puberty. They include:

  • Gender. Girls are 10 times as likely to have central precocious puberty as boys.
  • Genetics. Occasionally, precocious puberty can be triggered by genetic mutations that trigger the release of sex hormones. Most often these children have a parent or sibling with similar genetic abnormalities.
  • Race. Researchers don’t know why, but on average, African-American girls seem to start puberty about a year earlier than white girls. Some experts say that puberty should only be considered early in African-American girls if it happens before age 6.
  • International adoption. One study showed that children who are adopted from overseas are 10-20 times more likely to develop precocious puberty. Again, experts aren't sure why, but the uncertainty of the exact ages of the adopted children might bias the study results.
  • Obesity. A number of studies have shown an association between obesity in young girls and an increased risk of precocious puberty. However, researchers don't know how direct the link is. Obesity does not seem to be connected to early puberty in boys.

 

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Consequences of Early Puberty

For kids, early puberty can cause physical and emotional problems. They include:

  • Short stature. While kids with precocious puberty are often tall for their age, some wind up short as adults. Why? Once puberty is over, growth stops. Since precocious puberty ends earlier than normal puberty, these kids stop growing at an earlier age -- and sometimes, the end result may be a shorter height than they would have otherwise had.
  • Behavior problems. Some studies have found an association between early puberty and behavior problems, particularly in kids with developmental delays. However, many experts consider the evidence weak.
  • Early sexual activity. Although parents might worry, there's not strong evidence that kids with early puberty are likelier to be sexually active at a younger age.
  • Stress. Even when it's happening to average 12-year-olds, puberty can be a confusing time. It can be all the more stressful for younger kids with early puberty. They might feel awkward about looking different from their peers. Early menstruation can be unsettling for girls who are age 9 or younger -- or who are developmentally delayed. Parents can help by educating their kids about what changes they should expect.
  • Other risks. Some studies have found a link between early puberty in girls and a slightly increased risk of breast cancer later in life. However, the evidence is not clear. More research needs to be done.

Early Puberty: What Parents Should Remember

As a parent, it's easy to worry about early puberty. There's no doubt that you should take any signs seriously. If your child shows signs of early puberty, they should be evaluated by a pediatric endocrinologist.

But kids and their parents should not view precocious puberty as a fearful medical diagnosis.

Here are a few other things to remember:

  • Symptoms that might seem like early puberty are often unrelated and resolve on their own.
  • When a doctor and parents decide treatment is necessary, it is usually quite effective.
  • Most kids with signs of early puberty do fine, medically, psychologically, and socially.
WebMD Medical Reference Reviewed by Renee A. Alli, MD on June 13, 2017

Sources

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Carel, J. Pediatrics, April 2009.

eMedicine: "Precocious Puberty."

Ahmed M. Trends in Endocrinology and Metabolism, 2009.

Carel J. New England Journal of Medicine, May 29, 2008.

Cesario, S. Journal of Obstetric, Gynecologic, & Neonatal Nursing, May/June 2007.

The Hormone Foundation: "Hormones & You."

eMedicine: "Precocious Pseudo-Puberty."

Aksglaede L. Pediatrics, May 2009.

National Institute of Environmental Health Sciences: "Endocrine Disrupting Effects of BPA on Puberty and Estrogen Cycles."

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