Conclusions regarding epidemiology for obstetric ultrasound.

Received September 18, 2007, from the Department of Obstetrics and Gynecology, Rush University Medical Center, Chicago, Illinois USA (J.S.A.); Department of Radiology, University of Michigan Health System, Ann Harbor, Michigan USA (J.B.F.); Spectrum Research, Inc, Tacoma, Washington USA (A.C.S.); Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Rockville, Maryland USA (M.E.S.); and Center for Biomedical Physics, Temple University Medical School, Philadelphia, Pennsylvania USA (M.C.Z.). Revision requested September 20, 2007. Revised manuscript accepted for publication November 20, 2007. Address correspondence to Jacques S. Abramowicz, MD, Department of Obstetrics and Gynecology, Rush University Medical Center, 1653 W Congress Pkwy, Chicago, IL 60612 USA. E-mail: [email protected] Abbreviations CI, confidence interval; OR, odds ratio; RR, relative risk Statement