[1] Univ Calif San Francisco, Sch Med, Dept Obstet Gynecol & Reprod Sci, Bixby Ctr Global Reprod Hlth, San Francisco, CA 94143 USA
[2] Univ N Carolina, Sch Med, Dept Med, Div Infect Dis, Chapel Hill, NC USA
[3] Univ Calif Berkeley, Sch Publ Hlth, Dept Epidemiol, Berkeley, CA 94720 USA
[4] Univ Calif Berkeley, Sch Publ Hlth, Div Biostat, Berkeley, CA 94720 USA
[5] RTI Int, Womens Global Hlth Imperat, San Francisco, CA USA