[1] Univ Fed Pelotas, Postgrad Program Epidemiol, 1160 3 Floor, BR-96020220 Pelotas, RS, Brazil
[2] Univ Sao Paulo, Dept Med Prevent, Fac Med FMUSP, Sao Paulo, SP, Brazil
[3] Univ Bristol, MRC, Integrat Epidemiol Unit, Bristol, Avon, England
[4] Pontif Catholic Univ Rio Grande do Sul, Postgrad Program Pediat & Child Hlth, Porto Alegre, RS, Brazil