Although it is difficult to tease apart cause and effect, earlier puberty may have harmful impacts, especially for girls. Girls who go through puberty early are at a higher risk of depression, anxiety, substance abuse and other psychological problems, compared with peers who hit puberty later. Girls who get their periods earlier may also be at a higher risk of developing breast or uterine cancer in adulthood.
No one knows what risk factor — or more likely, what combination of factors — is driving the age decline or why there are stark race- and sex-based differences. Obesity seems to be playing a role, but it cannot fully explain the change. Researchers are also investigating other potential influences, including chemicals found in certain plastics and stress. And for unclear reasons, doctors across the world have reported a rise in early puberty cases during the pandemic.
“I don’t think there’s much controversy that obesity is a major contributor to early puberty these days,” said Dr. Natalie Shaw, a pediatric endocrinologist at the National Institute of Environmental Health Sciences who has studied the effects of obesity on puberty.
Still, she added, many girls who develop early are not overweight.
“Obesity can’t explain all of this,” Dr. Shaw said. “It’s just happened too quickly.”
