[1] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, Perinatol Res Branch, Program Perinatal Res & Obstet, Div Intramural Res,NIH, Bethesda, MD USA
[2] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, Perinatol Res Branch, Program Perinatal Res & Obstet, Div Intramural Res,NIH, Detroit, MI USA
[3] Univ Michigan, Dept Obstet & Gynecol, Ann Arbor, MI 48109 USA
[4] Michigan State Univ, Dept Epidemiol & Biostat, E Lansing, MI 48824 USA
[5] Wayne State Univ, Dept Med, Div Pulm Crit Care & Sleep Med, Detroit, MI 48202 USA