The incidence of premature puberty increased by 28 percent in the past three years in South Korea, a new study showed Wednesday.

According to data from the National Health Insurance Corporation, the number of children who reached puberty too early stood at 86,869 last year, up 28 percent from 2013 when the figure was 67,250. The 2016 figure means an incidence rate of 171.1 per 100,000 people, up from 134.5 in 2013.

Symptoms of precocious puberty include rapid growth, changes in body shape and size, and the development of the ability to reproduce before the age of 8 in girls and 9 in boys.

Sejong, a government administrative city some 130 kilometers southeast of Seoul, marked the highest rate of reported cases at 421.8 per 100,000 people.

Environmental hormones from new apartment buildings could lead to early puberty in children, said Jeong Eun-ah, head of Wooasung oriental medicine clinic.

“Another cause of the highest rate is that the city has a high influx of population, and the number of children moving here is rapidly increasing,” Jeong told The Korea Herald.

Without proper treatment, early puberty patients can suffer from reduced adult height later in life due a disorder in the growth plates, according to Samsung Medical Center in Seoul.

Regular exercise and a well-balanced daily diet can help prevent the early onset of puberty, the hospital’s experts say.

By Bak Se-hwan (sh@heraldcorp.com)