Extra weight may be sending U.S. girls into puberty earlier than ever, NBC News reported. Researchers have found that girls with higher body mass index may start developing breasts more than a year before their thinner friends - and perhaps as early as second grade. The earlier transition into puberty has sparked a whole new market of child-sized sanitary pads decorated with hearts and stars and deodorants aimed at 8-to-10 year olds, according to a new study and an editorial published Monday in the journal, Pediatrics. A team at the Cincinnati Children's Hospital Medical Center followed more than 1,200 girls ages 6 to 8 in three cities - San Francisco, Cincinnati and New York - from 2004 to 2011, and carefully documented their BMI and maturation process. Experts believe the extra weight might trigger the body to believe it has enough energy and other resources to start puberty, even though a child may be only 8-years-old.