[1] Brown Univ, Brown Ctr Study Children Risk, Warren Alpert Med Sch, Women & Infants Hosp Rhode Isl, Providence, RI 02905 USA
[2] Univ Kentucky Hosp, Lexington, KY USA
[3] Wayne State Univ, Dept Pediat, Detroit, MI 48202 USA
[4] Univ Miami, Miller Sch Med, Miami, FL 33136 USA
[5] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, Bethesda, MD USA
[6] RTI Int, Rockville, MD USA