1. Graduate Program in Child and Adolescent Health, School of MedicineUniversidade Federal do Rio Grande do Sul (UFRGS) Porto Alegre Brazil
2. Department of Social Medicine and Graduate Program in EpidemiologyUFRGS Porto Alegre Brazil
3. Graduate Program in Epidemiology, School of MedicineUFRGS Porto Alegre Brazil
4. Department of Statistics, Institute of Mathematics and StatisticsUFRGS Porto Alegre Brazil
5. Department of Pediatrics and Graduate Program in Child and Adolescent Health, School of MedicineUFRGS Porto Alegre Brazil