1. Bixby Center for Global Reproductive Health, Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of California, San Francisco, San Francisco, California, USA.
2. Department of Obstetrics and Gynecology, U.S. Naval Hospital Bremerton, Bremerton, Washington, USA.
3. Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California, USA.
4. Student Health Center, Ohlone College, Fremont, California, USA.
5. Student Health Services, Allan Hancock College, Santa Maria, CA, USA.