Affiliation: | a Department of Obstetrics and Gynecology, Women & Infants Hospital, Providence, RI b Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women's Hospital, and Planned Parenthood League of Massachusetts, Boston, MA c Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill, and Family Health International, Research Triangle Park, NC |