Accepted for Publication: August 27, 2014.
Published Online: November 3, 2014. doi:10.1001/jamapediatrics.2014.2365.
Study concept and design: Hawkins.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Hawkins.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Baum.
Obtained funding: Hawkins.
Administrative, technical, or material support: Hawkins, Gillman.
Study supervision: Hawkins, Oken, Gillman.
Conflict of Interest Disclosures: None reported.
Funding/Support: The research reported in this article was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health under award R00HD068506 to Dr Hawkins. Dr Oken was supported by grants P30 DK092924 and K24 HD069408.
Role of the Funder/Sponsor: The National Institutes of Health had no role in the design and conduct of the study; collection, management, analysis, or interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Additional Contributions: We thank Rachel Boyce, BS, data coordinator at the Harvard Center for Population and Development Studies, for data management, and the National Center for Health Statistics for the natality files. Ms Boyce was funded by award R00HD068506.