Timing and determinants of age at menarche in low-income and middle-income countries

Introduction: Understanding the timing and determinants of age at menarche is key to determining potential linkages between onset of puberty and health outcomes from a lifecourse perspective. Yet, we have little information in low- and middle-income countries (LMICs) mainly due to lack of data. The aim of this study is to analyse trends in the timing and the determinants of menarche in LMICs. Methods: Using 16 World Fertility Surveys and 28 Demographic and Health Surveys (DHS) from 27 countries, we analyse cohort trends and use fixed-effects models for DHS surveys to investigate socio-demographic and regional effects in the timing of age at menarche. Results: Trends of the mean age at menarche across time within and between countries show a declining or stalling path. Results of the determinants modelling show the relationship with wealth changes over time although not consistently across countries. We see a shift from poorer women having earlier menarche in earlier surveys to richer women having earlier menarche in later surveys in Indonesia, the Philippines and Yemen, whilst in Egypt the reverse pattern is evident. Conclusions: There is a considerable gap in both literature and data on menarche. We see a trend which is declining rapidly (from 14.66 to 12.86 years for the 1932 and 2002 cohorts respectively), possibly at a faster pace than high income countries and with a strong link to socio-economic status. This study calls for menarche questions to be included in more nationally-representative surveys and greater use of existing data because of its impact on life-course health in fast ageing settings. Further studies will need to investigate further the use of the age at menarche as an indicator of global health.