1. The National Center of Excellence in Women's Health, University of California, San Francisco, California.
2. Department of Epidemiology and Biostatistics, University of California, San Francisco, California.
3. Center for Reproductive Health Research and Policy, University of California, San Francisco, California.
4. National Center of Excellence in Women's Health, University of California, San Francisco, California.
5. National Center of Excellence in Women's Health and Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, California.