The age of menarche in Nigerian girls.

The median ages at menarche were obtained from a sample of 2029 urban and 328 rural Nigerian girls by the status quo method, and calculated by probits. The median age at menarche for the urban girls was 13-70 +/- 0-03 years whilst it was 14-50 +/- 0-09 years for the rural girls. There were significant differences in the median menarcheal ages of the girls according to the level of education and the occupation of the parents, and their geographical residence. The number of siblings and the birth rank of the girls did not influence the age of onset of menstruation. A secular trend towards earlier menarcheal age at a rate of 5 to 6 months per decade was observed amongst children of the professionally privileged group. The earliest menarche occurred amongst girls with university-educated fathers or mothers; in this group the median was 13-26 +/- 0-06 years, a value comparable with current European medians.