[1] London Sch Hyg & Trop Med, Dept Publ Hlth Environm & Soc, London WC1H 9SH, England
[2] London Sch Hyg & Trop Med, Dept Global Hlth & Dev, London, England
[3] Univ Exeter, Coll Med & Hlth, Peninsula Technol Assessment Grp, Exeter, Devon, England
[4] Georgetown Univ, Inst Reprod Hlth, Washington, DC USA