1. Department of Obstetrics and Gynecology; Stanford University School of Medicine; Stanford CA USA
2. Department of Obstetrics, Gynecology and Reproductive Sciences; San Francisco CA USA
3. Department of Epidemiology and Biostatistics; University of California; San Francisco CA USA
4. Stanford University School of Medicine; Stanford CA USA
5. Department of Obstetrics and Gynecology; Baylor College of Medicine; Houston TX USA
6. Department of Medicine; Positive Health Program at San Francisco General Hospital; University of California; San Francisco CA USA
7. University of Hawaii at Mãnoa School of Nursing and Dental Hygiene; Honolulu HI USA