1. Center for Birth Defects Research and Prevention, Massachusetts Department of Public Health; Boston Massachusetts
2. Division of Oncology and the Center for Pediatric Clinical Effectiveness; Children's Hospital of Philadelphia; Philadelphia Pennsylvania
3. Department of Obstetrics, Gynecology, and Reproductive Biology; Michigan State University; East Lansing Michigan
4. Department of Obstetrics and Gynecology; Dartmouth-Hitchcock; Lebanon New Hampshire
5. Department of Community Health Sciences; Boston University School of Public Health; Boston Massachusetts
6. Medical Genetics Unit, MassGeneral Hospital for Children; Boston Massachusetts