title: Response to 'what kind of controls to use in case control studies of malformed infants: recall bias versus "Teratogen nonspecificity" bias'
authors.affiliation: Departamento de Bioestadistica, Facultad de Medicina, Universidad Complutense, Madrid, Spain.
authors.initials: L
authors.lastname: Prieto
authors.initials: ML
authors.lastname: Martinez-Frias