The mystery surrounding why girls have been experiencing puberty at younger ages still hasn't been solved, and now new research shows that the same thing is happening to boys.
Researchers have found signs of puberty in American boys up to two years earlier than previously reported -- age 9 on average for blacks, 10 for whites and Hispanics (puberty is considered early in boys if it occurs by age 9 or earlier) . The study was published online in Pediatrics to coincide with the American Academy of Pediatrics' national conference in New Orleans.
Researchers recruited pediatricians in 41 states who participate in the academy's office-based research network. Doctors asked parents and boys aged 6 to 16 to take part during regular checkups between 2005 and 2010. Half of the boys were white, with the balance divided among blacks and Hispanics.
On average, white boys started puberty at age 10, a year and a half earlier than the normal average. For black boys, the average age of 9 was about two years earlier than in previous research. Among Hispanics, age 10 was similar to previous research that only involved Mexican-American boys; the new study included boys from other Hispanic backgrounds.
Testes enlargement was seen at age 6 in 9 percent of white boys, almost 20 percent of blacks and 7 percent of Hispanics. Pubic hair growth, another early sign of puberty, started about a year after testes enlargement in all groups but still earlier than previously thought.
Boys are more likely than girls to have an underlying physical cause for early puberty, but boys in this study were most likely free of any physical conditions that might explain the results, said lead author Marcia Herman-Giddens, a researcher at the University of North Carolina in Chapel Hill.
Theories about why this is happening range from higher levels of obesity, higher density of calories in processed foods, and physical inactivity, to chemicals in food and water. Any of those potential causes might interfere with normal hormone production, but so far none of them have been proven as a definite cause.
In girls, breast development is the first sign of early puberty, and research suggests that it starts at age 7 in about 10 percent of white girls, 23 percent of blacks and 15 percent of Hispanics -- far higher than rates reported more than a decade ago. Conversely, menstruation is starting only marginally earlier in girls today than 40 years ago.
Source: AP News
