1. University of Texas Houston School of Public Health, Dallas Regional Campus, Dallas, Texas.
2. Department of Epidemiology, University of Washington, Seattle, Washington.
3. Department of Pediatrics, University of Washington, Craniofacial Medicine, Craniofacial Clinic, Children's Craniofacial Center, Children's Hospital and Regional Medical Center, Seattle, Washington.
4. Department of Biostatistics, University of Washington, Seattle, Washington.
5. Departments of Pediatrics and Epidemiology, University of Washington and Children's Craniofacial Center, Children's Hospital and Regional Medical Center, Seattle, Washington