From the aDepartment of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA; bEpidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD.
Editor’s Note: Related articles appear on pp. 50, 58, and 67.
Disclosure: The authors report no conflicts of interest.
Correspondence to: Timothy L. Lash Department of Epidemiology Rollins School of Public Health Emory University 1518 Clifton Rd. NE, CNR 3 Atlanta, GA 30322 404.712.1270 firstname.lastname@example.org