Age of menarche and nutritional status of indigenous and non-indigenous adolescents in the Araucanía Region of Chile

Abstract

Background: Early onset of menarche has been linked to prevalence of obesity; however, this may differ for indigenous females.Objective: To analyse the relationship between age of menarche and nutritional status among indigenous and non-indigenous girls.Method: The design of this study was cross-sectional. Date of menarche was determined through interviews, and all responses were confirmed by the girls' mothers. A total of 8504 adolescents were screened for recent menarche. One hundred and thirty-one girls of Mapuche (indigenous) and 143 girls of Chilean–Spanish background were identified and evaluated by anthropometric measurements.Results: Median age of menarche was 150 months, interquartile range (IR) 143–157 in indigenous, and 145.5 months, IR 139–153 in non-indigenous girls (p = 0.04). The indigenous females showed a higher prevalence of overweight (36.4% vs 23.1%), although the frequency of obesity was similar (16.8% vs 16.3%). For indigenous girls, age of menarche was delayed by 2.69 months (confidence intervals (CI) –0.38 to 5.77). It was observed that girls with overweight experienced age of menarche 7.59 months earlier than those with normal weight, CI –10.78 to –4.41. In the analysis of obesity, the effect on age of menarche was similar, with onset 7.53 months earlier than for the normal weight, CI –11.34 to –3.72.Conclusion: Age of menarche is younger than has been previously reported and occurs earlier in girls with overweight and obesity, while being indigenous was not related.