Shape-shifting bodies. Cracking voices. Hairs sprouting in new places. Why do some children enter puberty early?
Girls who have their first period at a young age are more likely to experience poorer health as a adult, including an elevated risk of diabetes during pregnancy.
In developing countries, many girls feel unprepared when they go through puberty. And research indicates that low-income girls in the US may feel the same way.
Until now, the processes that lead some girls to start developing before others have been poorly understood.