1. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Florida College of Medicine, Gainesville, Florida 32610;
2. Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas 77030;
3. Department of Obstetrics and Gynecology and Women's Health, Albert Einstein College of Medicine, Yeshiva University, New York, NY 10461;
4. Division of Maternal Fetal Medicine, Long Island Jewish Medical Center, New Hyde Park, New York 11040;
5. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, College of Medicine, Ohio State University, Columbus, Ohio 43210;
6. Department of Obstetrics, Gynecology, and Reproductive Sciences, Institute of Human Genetics, University of California, San Francisco, California 94143;