[1] Duke Univ, Duke Clin Res Inst, Durham, NC 27708 USA
[2] Univ Miami, Dept Pediat, Coral Gables, FL 33124 USA
[3] Univ Massachusetts, Sch Med, Dept Pediat, Jamaica Plain, MA USA
[4] Columbia Univ, Dept Pediat, Med Ctr, New York, NY 10027 USA
[5] Ctr Dis Control & Prevent, Natl Ctr Birth Defects & Dev Disabil, Atlanta, GA USA
[6] Assoc Publ Hlth Labs, Silver Spring, MD USA
[7] Univ Rochester, Med Ctr, Dept Neurol, Rochester, NY 14642 USA
[8] Univ Michigan, Dept Pediat, Child Hlth Evaluat & Res Unit, Ann Arbor, MI 48109 USA
[9] Texas Dept State Hlth Serv, Austin, TX USA