[1] Univ Alabama Birmingham, Dept Obstet & Gynecol, Birmingham, AL 35294 USA
[2] Ctr Infect Dis Res Zambia, Lusaka, Zambia
[3] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, NIH, Bethesda, MD USA
[4] Univ N Carolina, Dept Med, Chapel Hill, NC USA
[5] Family Hlth Int, Durham, NC USA
[6] Muhimbili Univ Hlth & Allied Sci, Dept Microbiol & Immunol, Dar Es Salaam, Tanzania
[7] Drexel Univ, Coll Med, Dept Obstet & Gynecol, Philadelphia, PA 19104 USA