Onset of menarche by age 11 was assessed using one item scored as 0 (no) or 1 (yes) on the Pubertal Development Scale (Petersen et al. 1988). Although menarche occurs relatively late in the pubertal process, this salient event has greater immediate adaptive significance than other more gradual maturational processes (Ge et al. 2001) and allows for comparability with other studies.
