Published Online: May 13, 2013. doi:10.1001/jamapediatrics.2013.2364
Study concept and design: Visser, Danielson, and Perou.
Acquisition of data: Blumberg.
Analysis and interpretation of data: Visser, Danielson, Bitsko, and Blumberg.
Drafting of the manuscript: Visser and Danielson.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Visser and Danielson.
Administrative, technical, and material support: Visser and Bitsko.
Study supervision: Visser and Perou.
Conflict of Interest Disclosures: None reported.