The age of menarche.
D000293:Adolescent; D000367:Age Factors; D003710:Demography; D008572:Menarche; D008598:Menstruation; D011153:Population; D011154:Population Characteristics; D012098:Reproduction
Adolescents; Adolescents, Female; Age Factors; Demographic Factors; Menarche--determinants; Menstruation; Population; Population Characteristics; Reproduction; Youth