[1] Univ Washington, Sch Publ Hlth, Dept Global Hlth, Seattle, WA 98195 USA
[2] Johns Hopkins Univ, Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA
[3] Hosp Univ Penn, Dept Obstet & Gynecol, Philadelphia, PA 19104 USA
[4] Univ Washington, Dept Global Hlth, Seattle, WA 98195 USA
[5] Univ Washington, Dept Epidemiol, Seattle, WA 98195 USA
[6] Univ Washington, Dept Med, Seattle, WA USA
[7] Kenya Govt Med Res Ctr, Ctr Publ Hlth Res, Nairobi, Kenya
[8] World Hlth Org WHO, Dept Reprod Hlth & Res, Geneva, Switzerland
[9] Univ N Carolina, Gillings Sch Global Publ Hlth, Lineberger Comprehens Canc Ctr, Dept Epidemiol, Chapel Hill, NC 27599 USA