[1] Stanford Univ, Sch Med, Dept Epidemiol & Populat Hlth, Stanford, CA 94305 USA
[2] Univ Calif Berkeley, Sch Publ Hlth, Berkeley, CA USA
[3] Univ Calif Berkeley, Div Epidemiol & Biostat, Berkeley, CA USA
[4] Stanford Univ, Sch Med, Dept Pediat, Stanford, CA USA
[5] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA USA
[6] Stanford Univ, Calif Maternal Qual Care Collaborat, Stanford, CA USA
[7] Stanford Univ, Dept Obstet & Gynecol, Sch Med, Stanford, CA USA
[8] Stanford Univ, Dept Pediat,Sch Med, Div Neonatol, Perinatal Epidemiol & Hlth Outcomes Res Unit, Stanford, CA USA
[9] Calif Perinatal Qual Care Collaborat, Palo Alto, CA USA
[10] Case Western Reserve Univ, Dept Nutr, Cleveland, OH USA
[11] Stanford Univ, Sch Med, Dept Med, Stanford, CA USA