Background: Age at menarche is an important developmental milestone known to be modified by social and environmental factors. The determinants and potential change over time of age at menarche in Colombia are not well documented.

Aims: To obtain a current estimate of age at menarche in Colombia and to examine the associations between socio-demographic characteristics and age at menarche.

Subjects and methods: Between 1998 and 2001, we obtained recalled age at menarche, socio-demographic characteristics, and physical activity information in a group of 3206 students at the National University of Colombia who completed a self-administered questionnaire. We examined the cross-sectional associations between mean age at menarche and migratory pattern, parental education, socio-economic status indicators, practice of physical activity, and year of birth using linear regression.

Results: Mean age at menarche (± SD) was 12.68 ± 1.31. In a multivariate adjusted regression model, age at menarche was positively associated with family size and the practice of at least 2 daily hours of physical activity, and was inversely related to urbanization level, socio-economic status, and year of birth.

Conclusions: Socio-economic status is a strong predictor of menarche in this population. There appears to be a trend towards earlier menarche by year of birth.