*HealthDay News is reporting that the onset of puberty is continuing to drop among American girls, with many girls as young as 7 and 8 now showing the beginnings of breast development, new research shows.

Rising rates of childhood obesity — long linked to earlier sexual development — may be to blame, experts say.

In the study, more than 1,200 girls ages 6 to 8 from Cincinnati, East Harlem, N.Y. and San Francisco were examined on two occasions between 2004 and 2006 by two different female pediatricians or nurse practitioners who felt for the presence of breast tissue.

“We wanted to be careful not to mistake fatty deposits for actual breast tissue,” explained study author Dr. Frank Biro, director of adolescent medicine at Cincinnati’s Children’s Hospital.

Among 7-year-olds, about 10.4 percent of white girls, 23.4 percent of black girls and almost 15 percent of Hispanic girls had started developing breasts, the team report in the September issue of Pediatrics. Among 8-year-olds, 18.3 percent of white girls, about 43 percent of black girls and just under 31 percent of Hispanic girls showed evidence of breast development.

The figures suggest a rise in early-onset puberty compared to similar studies conducted earlier.

For 7-year-old white girls, especially, they show a doubling of the rate from as recently as a decade ago, Biro said. One study found that about 5 percent of white 7-year-old girls and 10.5 percent of 8-year-olds were showing breast development.

For black girls, the rate of breast development in that study was 15.4 percent for 7-year-olds and 36.6 percent for 8-year-olds.

The earlier data did not include information on Hispanic girls.

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