Assessment of the differences in Mean Age at Menarche (MAM) among adolescent girls in rural and urban Nigeria: a systematic review

Abstract

Introduction: Globally, there has been a decline in the age of menarche; the decline is higher in poorer countries than in richer ones. The measurement of the decline was based on the reported mean age at menarche (MAM) across the countries. There is a significant knowledge gap in investigating the generational decline in MAM in low- and median-income countries (LMC). In Nigeria, different studies have reported MAM, but none have attempted to investigate the generational shift in the reported MAM in girls residing in rural and urban areas. This review sought to understand if there is a rural-urban disparity in the MAM.

Methods: Documents were searched in the relevant bibliometric database and Population intervention, comparison(s) and outcome (PICO) framework were used as eligibility criteria for extracting data from the documents based on some inclusion and exclusion criteria. The population are adolescent schoolgirls in rural and urban settlements in Nigeria. The comparator is the age of menarche of urban versus rural adolescent schoolgirls in Nigeria, while the mean age at menarche (MAM) is the outcome. Data quality assessment was done to critically appraise the included studies and enhance. Data were synthesized using narrative review, descriptive and inferential statistics.

Results: Ten articles were included in the study, following the PRISMA framework. The overall mean evaluation of the risk of bias in the individual studies included in the review was computed to be 88%. Generally, there seems to be a decline in the age at menarche from 1976 to 2023. The rural MAM is higher than the urban MAM, and the gap between the two appears to be narrowing. The t-test showed no statistically significant mean differences between the rural and urban mean age at menarche (T = 2.1009, p value = 0.4679). The mean menarcheal age for girls in rural and urban areas is 13.44 and 13.04, respectively. There is a strong positive correlation between the rural and urban MAMs (Pearson = 0.93, p < 0.001). The Gaussian kernel estimated a bimodal distribution for rural girls, where they are most likely to experience menarche at 11 and 13 years, respectively, while urban girls are most likely to experience menarche at 13 years. In both locations, the incidence of menarche decreases just after the peak at 13 years.

Conclusion: Although rural girls have delayed menarche, there is no statistically significant mean difference between the age at menarche reported for rural and urban areas in Nigeria. Interventions in the form of counseling and reproductive education are recommended. The review provides a strong foundation for further research and policy development aimed at improving the health and well-being of adolescent girls in Nigeria and other similar settings.

Prospero registration: CRD42024529497.

Keywords: Correlation; Incidence; Menarche; Menstruation; PRISMA; Review; Statistics.

Fig. 1

PRISMA flow chart

Fig. 2

The line graph showing rural and urban MAM

Fig. 3

Scatter dots and trend line of Urban Versus Rural MAM

Fig. 4

The Gaussian Kernel Density estimation of the probability density of rural MAM

Fig. 5

The Gaussian kernel density estimation of the probability density of urban MAM