1 Department of Obstetrics and Gynecology, Family Planning Services and Research, Stanford University School of Medicine, Stanford, CA. Electronic address: ahenkel@stanford.edu.
2 Department of Obstetrics and Gynecology, Family Planning Services and Research, Stanford University School of Medicine, Stanford, CA; DuPont Clinic, Washington, DC.
3 Department of Obstetrics and Gynecology, Family Planning Services and Research, Stanford University School of Medicine, Stanford, CA.