[1] NICHD, Perinatol Res Branch, NIH, DHHS, Bethesda, MD USA
[2] NICHD, Perinatol Res Branch, NIH, DHHS, Detroit, MI USA
[3] Wayne State Univ, Dept Obstet & Gynecol, Sch Med, Detroit, MI 48201 USA
[4] Univ Michigan, Dept Obstet & Gynecol, Ann Arbor, MI 48109 USA
[5] Michigan State Univ, Dept Epidemiol & Biostat, E Lansing, MI 48824 USA
[6] Wayne State Univ, Harper Univ Hosp, Dept Pathol, Detroit, MI 48201 USA
[7] Wayne State Univ, Dept Pathol, Detroit, MI 48201 USA