1. Department of Obstetrics and Gynecology, University of Maryland School of Medicine, Baltimore, MD, USA;
2. Department of Public Health, California State University, Fullerton, Fullerton, CA, USA;
3. Department of Obstetrics and Gynecology, Oregon Health & Sciences University, Portland, OR, USA;
4. Department of Obstetrics and Gynecology, Loma Linda University School of Medicine, Loma Linda, CA, USA