The Launch of A Girl's First Period Study: Demystifying Reproductive Hormone Profiles in Adolescent Girls.

Limited data exist on the reproductive hormone dynamics that govern the transition from menarche to the establishment of the mature ovulatory cycles of a fertile young woman. It is also unclear how environmental and lifestyle factors could modulate this transition in contemporary girls. Here, we introduce A Girl's First Period Study, an ambitious longitudinal study aimed at charting the early post-menarchal course of a cohort of healthy girls in the Triangle region of North Carolina.