[1] Univ N Carolina, Sch Med, Dept Obstet & Gynecol, 3027 Old Clin Bldg,CB 7570, Chapel Hill, NC 27599 USA
[2] Univ N Carolina, Gillings Sch Global Publ Hlth, Dept Epidemiol, Chapel Hill, NC 27515 USA
[3] Univ N Carolina, Gillings Sch Global Publ Hlth, Dept Biostat, Chapel Hill, NC 27515 USA
[4] Univ N Carolina, Sch Med, Inst Global Hlth & Infect Dis, Chapel Hill, NC 27515 USA
[5] Stroger Hosp, Chicago, IL USA
[6] Suny Downstate Med Ctr, Coll Med, Div Infect Dis, Brooklyn, NY 11203 USA
[7] Albert Einstein Coll Med, Dept Epidemiol & Populat Hlth, Bronx, NY 10467 USA
[8] Georgetown Univ, Sch Med, Dept Infect Dis, Washington, DC USA
[9] Univ Southern Calif, Dept Prevent Med, Los Angeles, CA 90007 USA
[10] Univ Calif San Francisco, Dept Med, San Francisco, CA 94143 USA
[11] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Epidmiol, Baltimore, MD USA
[12] Emory Univ, Dept Med, Div Infect Dis, Atlanta, GA 30322 USA
[13] Univ Miami, Miller Sch Med, Dept Med, Miami, FL 33136 USA
[14] Univ Alabama Birmingham, Dept Biostat, Birmingham, AL USA