ERICA: age at menarche and its association with nutritional status.

OBJECTIVE To estimate the mean age at menarche and its association with nutritional status in Brazilian adolescents. METHODS The study sample included female adolescents aged 12-17 who participated in a multicenter, school-based, country-wide, cross-sectional study entitled The Study of Cardiovascular Risk in Adolescents (Estudo de Riscos Cardiovasculares em Adolescentes [ERICA]). Mean and median ages at menarche in Brazil were estimated. The association of age at menarche with sociodemographic data and nutritional status were described as means and their respective 95% confidence intervals. Survival analysis was used to assess the age at menarche according to nutritional status categories and the log-rank test was used to compare the medians. Bivariate and multivariate analyses were performed using Cox regression to verify the association between menarche and other variables. RESULTS A total of 73,624 students were evaluated, comprising 40,803 girls, of whom 37,390 reported menarche at a mean age of 11.71 years and a median of 12.41 years. Median age at menarche was lower in overweight and obese girls (p<0.001). The multivariate analysis showed that excess weight (HR=1.28; 95% CI 1.21-1.36; p<0.001) and studying in a private school (HR=1.06; 95% CI 1.02-1.10; p=0.003) were associated with menarche. CONCLUSIONS This is a pioneering study in Brazil with national and regional representativeness to estimate the mean and the median age of occurrence of menarche. Adolescents with excess weight had an earlier menarche than their peers, even after adjustment for confounding factors.