The influence of socioeconomic and nutritional status on menarche in Nigerian school girls.

A study of 352 randomly selected secondary school girls in an urban population in Southern Western Nigeria revealed a mean menarcheal age of 13.94 +/- 1.31 years and that 76.8% of girls attained menarche between ages 13 and 15 years. Age-matched pre- and post-menarcheal girls did not differ significantly in biophysical measurements, however, nutritional status was strongly and positively associated with attainment of menarche. School girls from the upper socio-economic class reached menarche 11 months earlier than the lower socio-economic counterparts. A significant finding of this study is that the declaration rate in age at menarche was slowest in girls from high socio-economic households. This deceleration was not influenced by body mass suggesting that socio-economic factors play a unique role in the secular trend widely reported in menarcheal age.