title: Dr. Durcan, et al reply.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; laurajanedurcan@hotmail.com.
authors.forename: Laura
authors.initials: L
authors.lastname: Durcan
authors.affiliation: Department of Epidemiology and Public Health, University of Maryland, College Park, Maryland, USA;
authors.forename: Laurence S
authors.initials: LS
authors.lastname: Magder
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Petri