[1] Univ Cape Town, Groote Schuur Hosp, Dept Obstet & Gynecol, ZA-7925 Cape Town, South Africa
[2] Univ Ibadan, Coll Med, Ibadan, Nigeria
[3] Univ Lagos, Coll Med, Teaching Hosp, Dept Obstet & Gynecol, Lagos, Nigeria
[4] Univ Pretoria, Dept Obstet & Gynecol, ZA-0002 Pretoria, South Africa
[5] Inkosi Albert Luthuni Cent Hosp, Dept Obstet & Gynecol, Durban, South Africa
[6] Univ Witwatersrand, Charlotte Maxeke Johannesburg Acad Hosp, Dept Obstet & Gynecol, Johannesburg, South Africa
[7] Univ Ghana, Sch Allied Hlth Sci, Dept Pathol, Accra, Ghana
[8] DDL Diagnost Lab, Rijswijk, Netherlands
[9] GlaxoSmithKline Pharmaceut Ltd, Bangalore, Karnataka, India
[10] GlaxoSmithKline Vaccines, Wavre, Belgium