Accepted for Publication: December 13, 2010.
Author Contributions: Dr Dutz had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Vera-Kellet and Dutz. Acquisition of data: Vera-Kellet, Elwood, and Dutz. Analysis and interpretation of data: Vera-Kellet, Peters, Elwood, and Dutz. Drafting of the manuscript: Vera-Kellet and Dutz. Critical revision of the manuscript for important intellectual content: Vera-Kellet, Peters, Elwood, and Dutz. Study supervision: Dutz.
Financial Disclosure: None reported.
Funding/Support: Dr Vera-Kellet was supported by a scholarship from the Chile Bicentennial Scholarship (Becas Chile) and Pontificia Universidad Cat ólica de Chile. Dr Dutz was supported by a senior scientist award from the Child and Family Research Institute and is a senior scholar with the Michael Smith Foundation.