[1] United BioSource Corp, Bethesda, MD 20814 USA
[2] Univ N Carolina, Chapel Hill, NC USA
[3] Sahlgrens Univ Hosp, Dept Obstet & Gynecol, Gothenburg, Sweden
[4] Univ Roma La Sapienza, SanAndrea Hosp, Rome, Italy
[5] Royal Hallamshire Hosp, Sheffield S10 2JF, S Yorkshire, England
[6] Hosp Univ Penn, Philadelphia, PA 19104 USA
[7] Pfizer Inc, New York, NY USA