Drs. Julianna Deardorff and Louise Greenspan are co-investigators of a study showing that girls bodies are changing at an earlier age. Currently, 15% of girls under age eight are showing signs of puberty compared to 5% just 20 years ago. Why is puberty starting sooner? I spoke to Dr. Louise Greenspan, co-author of The New Puberty: How to Navigate Early Development in Today's Girls, about this and what parents and schools can do to help their girls during this transition.