[1] Univ Miami, Miller Sch Med, Dept Pediat, Miami, FL 33136 USA
[2] RTI Int, Stat & Epidemiol, Res Triangle Pk, NC 27709 USA
[3] Wayne State Univ, Sch Med, Dept Pediat, Detroit, MI 48201 USA
[4] Univ Kentucky Hosp, Dept Pediat, Lexington, KY 40506 USA
[5] Brown Univ, Women & Infants Hosp Rhode Isl, Brown Ctr Study Children Risk, Warren Alpert Med Sch,Dept Pediat, Providence, RI 02903 USA
[6] Univ Tennessee, Hlth Sci Ctr, Boling Ctr Dev Disabil, Memphis, TN 38105 USA