A new research has revealed that the puberty age in girls is starting early as compared to previous times. Nowadays, girls begin developing breasts at the age of 7. There are growing concerns about this trend and researchers are trying to locate the causes behind it.

Researcher Frank M. Biro, MD, Director of the division of adolescent medicine at Cincinnati Children's Hospital Medical Center, Cincinnati, says that body composition and ethnicity has a major role in leading to puberty before time.

It is deemed that higher rates of obesity can also cause earlier puberty, as body fat can generate sex hormones. Another research indicates that ecological chemicals, which have effect like estrogen, might also be a reason. However, this concept has not been proved as yet.

Biro tells WebMD, "We found that girls who are African-American matured before whites, and that's been shown in several studies. White girls are maturing earlier than they had before, compared to 20 years earlier".

In a trial that entailed 1,239 girls, Biro discovered that 10% of whites, 23% of African-Americans, and 15% of Hispanic girls, had started developing breasts from age 7, signalling the rise of early puberty.

The research appeared in the online issue of the journal Pediatrics.