Menarche, the onset of first menstruation in girls, indicates the attainment of reproductive capacity and is a widely used marker of pubertal timing. Age at menarche varies widely between girls and is highly dependent on nutritional status1. Early menarche is associated with several adverse health outcomes, including breast cancer2, endometrial cancer3, obesity4, type 2 diabetes5 and cardiovascular disease6, and also shorter adult stature4. Studies of twins and extended families, albeit largely performed in populations free of nutritional deprivation, estimate that around 50% of the variance in menarche timing is attributable to genetic factors in such settings7.
