Média da idade da menarca no Brasil e sua associação com o estado nutricional e resistência insulínica em adolescentes: Projeto ERICA

Abstract

Menarche usually occurs between 12 and 13 years old, influenced by a combination of genetic, social and environmental factors. Studies have shown that higher body mass index during childhood is related to early onset of puberty. And the anticipation of menarche has been implicated in persistent obesity, type 2 diabetes mellitus, cardiovascular incidents and increased overall mortality. The objective of the present study was to estimate the mean age of menarche and its association with sociodemographic data, nutritional status and insulin resistance in Brazilian adolescents. The study sample included female adolescents aged 12 to 17 who participated from a multicenter, school-based country-wide cross-sectional study - The Study of Cardiovascular Risk in Adolescents (Portuguese acronym, ERICA ). Mean and median age of occurrence of menarche in Brazil were estimated. And association of menarche age with sociodemographic data, nutritional status and the components of glucose metabolism were described as means and their respective 95% confidence intervals. Survival analysis was used to explore the age of menarche according to nutritional status categories and the log-rank test was used to compare the medians. Pearson correlation was performed between the variables age of menarche and index homeostasis model assessment of insulin resistance (HOMA-IR). A total of 40,803 adolescents were evaluated, of which 37,390 reported menarche, with a mean age of 11.71 years and a median 12.41 years. Black adolescents presented lower mean age, but with no statistically significant difference. The correlation coefficient between age of menarche and HOMA-IR index was -0.03 (p <0.001). Median age at menarche was lower in those with overweight and obesity (p <0.001). This is a pioneering study in Brazil with national and regional representativeness to estimate the mean and the median age of occurrence of menarche. Since adolescents with overweight and adolescents with a high HOMA-IR index had earlier menarche and this has been associated with comorbidities in adolescence and adulthood, measures should be taken in relation to the increasing rates of obesity in the population, including in Brazil.