[1] Korle Bu Teaching Hosp, Dept Obstet & Gynaecol, Accra, Ghana
[2] Univ Ghana, Sch Med, Dept Haematol, Accra, Ghana
[3] Vanderbilt Childrens Hosp, Vanderbilt Ctr Excellence Sickle Cell Dis, Nashville, TN USA
[4] Vanderbilt Univ, Sch Med, 221 Kirkland Hall, Nashville, TN 37235 USA
[5] Univ Ghana, Sch Med, Dept Physiol, Accra, Ghana
[6] Univ Ghana, Sch Med, Dept Child Hlth, Accra, Ghana
[7] Aminu Kano Teaching Hosp, Kano, Nigeria
[8] Washington Univ, Dept Obstet & Gynecol, St Louis, MO USA
[9] Univ Ghana, Sch Med, Dept Obstet & Gynaecol, POB 4236, Accra, Ghana