[1] Brown Univ, Women & Infants Hosp, Dept Pediat, Providence, RI 02905 USA
[2] RTI Int, Stat & Epidemiol Unit, Res Triangle Pk, NC USA
[3] Brown Univ, Women & Infants Hosp, Dept Psychiat & Human Behav, Ctr Study Children Risk,Brown Alpert Med Sch, Providence, RI USA
[4] Univ Alabama Birmingham, Div Neonatol, Birmingham, AL USA
[5] Univ Utah, Sch Med, Dept Pediat, Div Neonatol, Salt Lake City, UT USA
[6] Univ Cincinnati, Dept Pediat, Cincinnati Childrens Hosp Med Ctr, Cincinnati, OH 45221 USA
[7] Duke Univ, Dept Pediat, Durham, NC 27706 USA
[8] Indiana Univ Sch Med, Dept Pediat, Indianapolis, IN USA
[9] Case Western Reserve Univ, Rainbow Babies & Childrens Hosp, Dept Pediat, Cleveland, OH 44106 USA
[10] Univ Iowa, Dept Pediat, Iowa City, IA 52242 USA
[11] Wayne State Univ, Dept Pediat, Detroit, MI 48202 USA
[12] Emory Univ, Sch Med, Dept Pediat, Atlanta, GA USA
[13] Childrens Healthcare Atlanta, Atlanta, GA USA
[14] Floating Hosp Children, Tufts Med Ctr, Dept Pediat, Div Newborn Med, Boston, MA USA
[15] Univ Texas SW Med Ctr Dallas, Dept Pediat, Dallas, TX 75390 USA
[16] Stanford Univ, Sch Med, Dept Pediat, Palo Alto, CA 94304 USA
[17] Yale Univ, Sch Med, Dept Pediat, New Haven, CT 06510 USA
[18] Univ New Mexico, Hlth Sci Ctr, Albuquerque, NM 87131 USA
[19] RTI Int, Stat & Epidemiol Unit, Rockville, MD USA
[20] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, NIH, Bethesda, MD USA