Biosocial factors affecting menarche in a mixed Nigerian population.

A prospective study of school girls in a mixed Nigerian population revealed that the mean menarcheal age was 13.98 +/- 1.30 years. The mean menarcheal age was influenced by the social class of the parents, being higher in the lower social class, there were considerable variations in the biologic measurements (height, weight and body mass index) among girls who attained menarche.