Accepted for Publication: September 5, 2013.
Published Online: January 6, 2014. doi:10.1001/jamapediatrics.2013.4347.
Study concept and design: Roman, Raffo, Meghea.
Acquisition of data: Roman, Zhu, Meghea.
Analysis and interpretation of data: All authors.
Drafting of the manuscript: All authors.
Critical revision of the manuscript for important intellectual content: Roman, Raffo, Meghea.
Statistical analysis: Raffo, Zhu, Meghea.
Obtained funding: Roman, Meghea.
Administrative, technical, or material support: Raffo.
Study supervision: Meghea.
Conflict of Interest Disclosures: None reported.
Funding/Support: This study was supported in part by the Michigan Department of Community Health.
Role of the Sponsor: The funding source 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.
Additional Contributions: Joseph Gardiner, PhD, and Zhehui Luo, PhD, provided advice on the propensity score–matching method, reviewed findings, and provided critical review during manuscript preparation; Claudia Holzman, DVM, MPH, PhD, provided advice on preterm birth and low birth weight and critical review during manuscript preparation. Drs Gardiner, Luo, and Holzman did not receive any financial compensation for their work.