1. Department of Obstetrics and Gynecology, UCLA, Los Angeles, CA 90095, USA
2. The Wharton School, University of Pennsylvania, Philadelphia, PA 19104, USA
3. Division of General Internal Medicine and Health Services Research, UCLA, Los Angeles, CA 90095, USA
4. Fertility and Surgical Associates of California, Thousand Oaks, CA 91361, USA
5. Department of Health Policy, Management and Behavior, School of Public Health, University at Albany, SUNY, Albany, NY 12222, USA
6. Department of Obstetrics & Gynecology, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
7. Department of Healthcare Organization and Policy, School of Public Health, University of Alabama at Birmingham, Birmingham, AL 35294, USA