[1] Univ Southern Calif, Keck Sch Med, Dept Obstet & Gynecol, Div Maternal Fetal Med, Los Angeles, CA USA
[2] Univ Southern Calif, Keck Sch Med, Childrens Hosp Los Angeles, Dept Pediat, Los Angeles, CA USA
[3] Childbirth Res Associates, North Hollywood, CA USA
[4] Univ Southern Calif, Keck Sch Med, Childrens Hosp Los Angeles, Div Neonatol,Dept Pediat, Los Angeles, CA USA
[5] Childrens Hosp Los Angeles, Fetal & Neonatal Inst, Los Angeles, CA 90027 USA