About the Authors
- Aluísio J. D. Barros, Cesar G. Victora
- Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil
The authors have declared that no competing interests exist.
Analyzed the data: AJB CGV. Wrote the first draft of the manuscript: AJB CGV. Contributed to the writing of the manuscript: AJB CGV. ICMJE criteria for authorship read and met: AJB CGV. Agree with manuscript results and conclusions: AJB CGV.