[1] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Hlth Behav & Soc, Baltimore, MD USA
[2] Johns Hopkins Bloomberg Sch Publ Hlth, Ctr Injury Res & Policy, Dept Hlth Policy & Management, Baltimore, MD USA
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Populat Family & Reprod Hlth, Baltimore, MD USA
[4] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Behav Sci & Community Hlth, Pittsburgh, PA 15260 USA
[5] Univ Pittsburgh, Ctr Injury Res & Control, Pittsburgh, PA 15260 USA
[6] George Washington Univ, Sch Publ Hlth & Hlth Serv, Dept Prevent & Community Hlth, Maternal & Child Hlth Program, Washington, DC 20052 USA
[7] St Michaels Hosp, Ctr Res Inner City Hlth, Toronto, ON M5B 1W8, Canada
[8] Univ Toronto, Toronto, ON, Canada