[1] Univ Calif San Diego, Dept Reprod Med, Div Maternal Fetal Med, San Diego, CA 92103 USA
[2] Korle Bu Teaching Hosp, Dept Obstet & Gynecol, Accra, Ghana
[3] Univ Ghana, Sch Biomed & Allied Hlth Sci, Dept Physiol, Accra, Ghana
[4] Univ Ghana, Sch Med & Dent, Dept Obstet & Gynecol, Accra, Ghana
[5] Univ Calif San Diego, Sch Med, San Diego, CA 92103 USA