Accepted for Publication: January 21, 2015.
Published Online: April 13, 2015. doi:10.1001/jamapediatrics.2015.0187.
Study concept and design: Sivertsen, Harvey, Reichborn-Kjennerud, Hysing.
Acquisition, analysis, or interpretation of data: Sivertsen, Reichborn-Kjennerud, Torgersen, Ystrom, Hysing.
Drafting of the manuscript: Sivertsen, Harvey, Hysing.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Sivertsen, Hysing.
Obtained funding: Sivertsen, Hysing.
Study supervision: Reichborn-Kjennerud.
Conflict of Interest Disclosures: None reported.
Funding/Support: The Norwegian Mother and Child Study is supported by the Norwegian Ministry of Health and the Ministry of Education and Research, National Institutes of Health [NIH]/National Institute of Environmental Health Sciences (contract NO-ES-75558), NIH/National Institute of Neurological Disorders and Stroke (grant 1 UO1 NS 047537-01), and the Norwegian Research Council/FUGE (grant 151918/S10).
Role of the Funder/Sponsor: The funding organizations had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Additional Contributions: We are grateful to all the participating families in Norway who have taken part in this ongoing cohort study.