Why girls are starting their menstruation earlier

*In this article, the term “precocious puberty” is used to refer to “idiopathic central precocious puberty”

Precocious puberty, the early onset of puberty, is becoming increasingly common among young girls, raising concerns among healthcare providers and parents.

Sena Orsdemir, MD, medical director of the Loma Linda University Children's Hospital Pediatric Diabetes and Endocrine Center, sheds light on this condition, its causes, diagnosis, and potential impacts on affected children.

What is central precocious puberty?

"Puberty is a natural process where the body transitions from childhood to adulthood through hormonal changes," Orsdemir said. "In cases of precocious puberty, these changes happen earlier than usual, sometimes significantly so. This is the same biological process, just accelerated."

While the typical age for girls to start their first menstrual cycle is around 12.5 years, precocious puberty can cause this to happen much earlier. Girls in the U.S. are now getting their first menstrual period about six months earlier on average compared to the 1950s and '60s. Also, more girls begin menstruation before age 9, which is considered unusually early. These findings come from a large new study published in the journal JAMA Network Open.

Why is this happening?

"It's a complex, multifactorial issue, and while we see strong associations, it's challenging to say definitively that one specific factor is to blame."

Orsdemir says obesity and poor nutrition are significant contributors. "Increased body fat is strongly associated with the early onset of puberty, particularly in girls," she says. A diet high in calories and processed foods is also one of the top reasons.

Environmental factors also play a role. Endocrine disruptors—chemicals in plastics, pesticides, and other products—can interfere with hormone systems.

Precocious puberty diagnosis typically starts with a parent or pediatrician noticing signs of early puberty, such as breast development. Blood tests are then used to measure hormone levels. If hormone levels are elevated, it confirms the diagnosis of central precocious puberty. The early onset of puberty can impact final adult height and potentially lead to earlier menopause. Beyond the physical implications, precocious puberty can have significant psychological and social effects. "Girls going through puberty at a much younger age can face increased risk of anxiety and bullying," Orsdemir said.

For treatment, pediatric endocrinologists may use GnRH analogs—medications that, when administered, stop the progression of puberty. These treatments, also known as puberty blockers, are available as injections or implants.

What can parents do?

For parents concerned about precocious puberty, Orsdemir recommends seeking a comprehensive evaluation at a pediatric endocrine clinic, where physicians can develop individualized care and treatment plans.

To learn more or to schedule an appointment at the Pediatric Diabetes and Endocrine Center, visit online.