The pattern of early menstrual cycles in Nigerian girls

Between October 1980 and June 1981 a total of 2528 recorded menstrual cycles were collected from 422 girls in four girls' secondary schools at Enugu and Nuskka in Anambra State, Nigeria. The mean and standard deviation for all cycles were 30.9 and 18.60 days, respectively. The results support the findings from other parts of the World that menstrual cycles are highly irregular during the first few years after menarche and that the variability of these cycles decreases as menstrual life continues. A comparison between the pattern of irregularity indicated in our study and those of earlier studies in North America and Europe at different time points suggests that socio-economic development, with its attendant improvements in nutrition and the elimination of infectious diseases, may be helping to bring about a reduction in the variability of early menstrual cycles, the reduction being particularly significant in respect of very long cycles.