Timing of pubertal growth and menarche in indigenous Qom girls of Argentina.

Background: Pubertal timing is in part mediated by environmental factors, with greater energy availability often associated with earlier or more rapid development. Many indigenous populations are undergoing socioeconomic change that may affect pubertal development and related health risks, necessitating fundamental longitudinal research on growth and development in these populations.

Aim: Growth velocity and time to menarche among peri-urban indigenous Qom (Toba) girls in Argentina are described.

Subjects And Methods: From 2011-2015, monthly anthropometrics and menstrual status were collected from 61 Qom girls aged 7-14. Growth velocity curves were generated using the 'Super-imposition by translation and rotation' (SITAR) method. Median time to menarche was estimated by Kaplan-Meier survival analysis.

Results: Mean ages at peak height, weight and BMI velocity were estimated at 10.8, 10.5 and 10.7 years and median age at menarche at 11.6 years (95% CI = 11.4-11.9). At menarche, 45% of girls were overweight or obese and only one participant was short-statured by international standards.

Conclusion: Qom participants in this study exhibit relatively fast pubertal development as compared to other Latin American indigenous populations studied previously by others. Genetic and environmental factors influencing body size, diet and/or activity levels should be investigated further in this population.