The most probable explanation for why periods and breast development might be happening younger is that girls tend to weigh more today than they did a generation ago—and this higher body fat percentage is leading to earlier activation of the pituitary gland, which produces the hormones responsible for puberty.
Researchers and physicians hypothesized about possible causes for the increase in early puberty, such as increasing rates of obesity; greater exposure to endocrine-disrupting chemicals found in food, plastics, and personal-care products; and stressful or abusive home environments.
Some causes of early puberty in girls include thyroid disorders, abnormal brain structure, exposure to radiation therapy, or ovarian cysts. Genetic conditions may result in early puberty and can be detected with testing. In 90% of cases in girls, however, there is no known cause.
Most girls start their periods when they're about 12, but they can start as early as 8, so it's important to talk to girls from an early age to make sure they're prepared.
Most young people will have their first periods when they're between 11 and 14½, but anywhere from 9-16 years is considered normal. Periods are likely to start soon if your child has: had a major growth spurt. grown some underarm and pubic hair.
Girls usually stop growing taller about 2 years after starting their menstrual period. Your genes (the code of information you inherited from your parents) will decide many things during this time, including: your height, your weight, the size of your breasts and even how much hair you have on your body.
Higher total protein, animal protein and meat intake in children ages 3 to 7 have been associated with earlier onset of menstruation. High protein intake elevates IGF-1 levels and promotes growth, which could accelerate the onset of puberty.
It's not uncommon for young children to show certain traits associated with puberty, including some pubic hair, underarm hair and the beginnings of breast development, said Dr. Paul Kaplowitz, who led the American Academy of Pediatrics report.
Premature pubarche, or the development of pubic hair before the age of 8 in girls or 9 in boys, is most commonly caused by premature adrenarche. Adrenarche is the maturation of the adrenal zona reticularis in both boys and girls, resulting in the development of pubic hair, axillary hair, and adult apocrine body odor.
Boys tend to show the first physical changes of puberty between the ages of 10 and 16. They tend to grow most quickly between ages 12 and 15. The growth spurt of boys is, on average, about 2 years later than that of girls. By age 16, most boys have stopped growing, but their muscles will continue to develop.
But it's perfectly normal for puberty to begin at any point between the ages of 8 and 13 in girls and 9 and 14 in boys. There's not usually any need to worry if puberty does not start around the average age, but it's a good idea to speak to your GP for advice if it starts before 8 or has not started by around 14.
African-American and Hispanic girls tend to reach puberty earlier than their white counterparts, research shows.
Among adolescent girls, early puberty is associated with more depressive disorders, substance use disorders, eating disorders and disruptive behavior disorders. Of those disorders, "the clearest and most consistent link is between early puberty and depression in girls," Graber says.
Precocious puberty is less common in boys, and more likely to be related to another medical problem. For about 5% of boys, the condition is inherited. Some very young girls (usually from 6 months to 3 years old) may show breast development that later disappears or may last but without other physical changes of puberty.
There's really no right or wrong age for kids to begin shaving. It all depends on when their body changes and their interest level. For instance, some girls start puberty as young as age 8 or 9, while boys start puberty a little later.
Median age of development of hair in the scrotal area was 4.5 months (range, 3 to 7 months). Median age at presentation was 7 months (range, 4 to 10 months). On clinical examination, all 9 infants had more than 10 long pigmented hairs on the scrotum, except for 1 infant who had only 5 dark hairs.
Short height.
Children with precocious puberty may grow quickly at first and be tall, compared with their peers. But, because their bones mature more quickly than normal, they often stop growing earlier than usual. This can cause them to be shorter than average as adults.
“There is no right or certain age to start shaving,” said Rashell Orey, a licensed master social worker at Banner Health. “Some may be eager to start very early, while for others, this could be a scary thought. It's a conversation that you'll need to discuss with them.”
Both hormones are specific to cows and have no effect on the human body. Thus, the hormones in milk are not a valid explanation for early puberty. Milk is a significant source of calcium and other essential nutrients and should not be eliminated during the adolescent years.
The “unhealthy diet” pattern was significantly positively associated with precocious puberty in both boys (OR = 1.24, 95% CI = 1.02–1.51) and girls (OR = 1.31, 95% CI = 1.10–1.56).
Girls who drink more sugary beverages start their periods earlier than girls who consume fewer. That's the finding of a new study, and it suggests that this consumption is somehow linked to the onset of puberty. The association remained even once the girls' weight and height had been controlled for.
Your Daughter's Body
They're likely to stand somewhere between 4 and 5 feet tall at this age. Their weight will probably be somewhere between 70 and 100 pounds.
How Tall Should a 12 Year Old Be? We can only speak to national average heights here in North America, whereby, a 12 year old girl would be between 137 cm to 162 cm tall (4-1/2 to 5-1/3 feet). A 12 year old boy should be between 137 cm to 160 cm tall (4-1/2 to 5-1/4 feet).
Myth: menarche means the end of growth is near
The reality is that the average gain in height after menarche is about 7 cm (3 inches), and it is even greater for girls who menstruate on the early side of normal.