Accepted for Publication: February 6, 2013.
Published Online: August 12, 2013. doi:10.1001/jamapediatrics.2013.2230.
Acquisition of data: Yorifuji, Inoue.
Analysis and interpretation of data: Yamakawa, Kato.
Drafting of the manuscript: Yamakawa.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Yamakawa, Kato.
Obtained funding: Yorifuji.
Administrative, technical, and material support: Yorifuji, Inoue.
Study supervision: Doi.
Conflict of Interest Disclosures: None reported.
Funding/Support: This work was supported in part by Ministry of Health, Labour, and Welfare Health and Labour Sciences Research Grants on Health Research on Children, Youth, and Families as well as a Grant for Environmental Research Projects from the Sumitomo Foundation.
Additional Contributions: We thank Yoshitada Yamauchi, MD, Eiji Yamamoto, PhD, and Masaya IIzuka, PhD, for kind advice. We also thank Akiko Tokinobu, MMS, for support.