Is puberty starting earlier?

As a pediatrician, parents often ask me when their child will go into puberty. While the answer is slightly different for each child, it is very interesting to note over the past two decades how secondary changes in girls and boys are occurring at a younger age.

In the past Century, the average age when girls start menstruating is less than 12.5 years, and it appears to be declining. While studies are not as clear with boys, it appears that puberty is starting six months to two years earlier as well. 

Four key factors seem to be influencing this change:

1. Obesity: The rate of obesity has more than doubled in the past 30 years. Estrogen is produced not only in the ovaries, but also in fat cells. Increased estrogen will result in breast development. With the ovaries having increased estrogen on a regular basis, then there will likely be an earlier and prolonged puberty.
2. Endocrine disrupters: These agents mimic the effects of estrogen in the body and can potentially trigger breast growth. They also accumulate in the fatty tissue and tend to break down slowly. Children’s bodies are more sensitive to exposure to them. Examples include polychlorinated biphenyls, Bisphenol A, phthalates and pesticides. These chemicals are in a lot of the day-to-day products that we use. BPA is used in rigid cups, water bottles, food storage containers and can liners. They can leach from these containers into food and beverages during heating and washing. Phthalates can be found in some toys, food packaging, shampoos and detergents to name a few. Endocrine disrupters are also found in pesticides, fuels and industrial chemicals.
3. Childhood stress: This may include conflict in a child’s environment or the absence of a biological parent.
4. Ethnicity: In certain populations, puberty seems to be occurring earlier as well. African American girls seem to have breast development about a year earlier than their white peers. Data from 2013 shows that in the United States 23% of black girls, 15% of Hispanic girls and 10% of white girls had started to develop breasts by age seven.

Precocious puberty — the onset of signs of puberty before age 7 or 8 in girls and age 9 in boys — can be physically and emotionally difficult for kids and is sometimes the sign of a health problem. Once puberty occurs, physical growth tends to stop. Children having earlier puberty likely are at greater risk for short stature. While there is no correlation between age of onset of puberty and one's social or emotional maturation, there may likely be increased stress, depression and anxiety.

If you have questions about your child’s development, talk with his or her pediatrician.