[1] Emory Univ Sch Med, Dept Pediat, Atlanta, GA 30322 USA
[2] Childrens Healthcare Atlanta, Atlanta, GA USA
[3] RTI Int, Stat & Epidemiol Unit, Res Triangle Pk, NC USA
[4] Univ Iowa, Dept Pediat, Iowa City, IA 52242 USA
[5] Univ Texas SW Med Ctr Dallas, Dept Pediat, Dallas, TX 75390 USA
[6] Wayne State Univ, Dept Pediat, Detroit, MI 48202 USA
[7] Brown Univ, Women & Infants Hosp, Dept Pediat, Providence, RI 02908 USA
[8] RTI Int, Stat & Epidemiol Unit, Rockville, MD USA
[9] Case Western Reserve Univ, Rainbow Babies & Childrens Hosp, Dept Pediat, Cleveland, OH 44106 USA
[10] Ctr Dis Control & Prevent, Atlanta, GA USA
[11] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, NIH, Bethesda, MD USA