[1] Univ Rochester, Sch Med & Dent, Dept Pediat, Div Neonatol, Rochester, NY 14642 USA
[2] Univ Rochester, Sch Med & Dent, Rochester, NY USA
[3] Univ Calif Berkeley, Berkeley Sch Publ Hlth, Berkeley, CA 94720 USA
[4] Stanford Univ, Dept Pediat, Sch Med, Div Neonatal & Dev Med, Stanford, CA 94305 USA
[5] Calif Perinatal Qual Care Collaborat, Stanford, CA USA